snyk/snyk-demo-app

A demo application for Snyk.
Vulnerabilities 28 via 109 paths
Dependencies 243
Source GitHub
Commit 2f31650f

Snyk continuously finds and fixes vulnerabilities in your dependencies.

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high severity

Arbitrary Code Injection

  • Vulnerable module: pouchdb
  • Introduced through: falcor-router-demo@1.0.3

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d falcor-router-demo@1.0.3 pouchdb@3.6.0

Overview

pouchDB is an open-source JavaScript database inspired by Apache CouchDB that is designed to run well within the browser.

Vulnerable versions of the package had the evalView function in pouchdb-core to execute the view function without a sandbox. The fix was introduced in version 6.0.5, executing the view function in a sandbox and enforcing strict mode when running in Node.js.

The vulnerability was reported by micaksica.

Remediation

Upgrade pouchDB to version 6.0.5 or later.

References

high severity

Denial of Service (Memory Exhaustion)

  • Vulnerable module: qs
  • Introduced through: falcor-router-demo@1.0.3

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d falcor-router-demo@1.0.3 pouchdb@3.6.0 request@2.28.0 qs@0.6.6
    Remediation: Upgrade to falcor-router-demo@1.0.5.

Overview

qs is a querystring parser that supports nesting and arrays, with a depth limit.

Affected versions of this package are vulnerable to Denial of Service (Dos) attacks. During parsing, the qs module may create a sparse area (an array where no elements are filled), and grow that array to the necessary size based on the indices used on it. An attacker can specify a high index value in a query string, thus making the server allocate a respectively big array. Truly large values can cause the server to run out of memory and cause it to crash - thus enabling a Denial-of-Service attack.

Remediation

Upgrade qs to version 1.0.0 or greater. In these versions, qs introduced a low limit on the index value, preventing such an attack

References

high severity

Denial of Service through invalid If-Modified-Since/Last-Modified headers

  • Vulnerable module: hapi
  • Introduced through: hapi@10.5.0

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0
    Remediation: Upgrade to hapi@11.1.3.

Overview

Sending a purposefully crafted invalid date in the If-Modified-Since or Last-Modified header will cause the Hapi server to err but keep the socket open (the socket will time out after 2 minutes by default). This allows an attacker to quickly exhaust the sockets on the server, making it unavailable (a Denial of Service attack).

The vulnerability is caused by the combination of two bugs. First, the underlying V8 engine throws an exception when processing the specially crafted date, instead of stating the date is invalid as it should. Second, the Hapi server does not handle the exception well, leading to the socket remaining open.

Upgrading Hapi will address the second issue and thus fix the vulnerability.

References

high severity

Improper minification of non-boolean comparisons

  • Vulnerable module: uglify-js
  • Introduced through: snyk-demo-child@0.0.1

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d snyk-demo-child@0.0.1 handlebars@3.0.3 uglify-js@2.3.6
    Remediation: Run snyk wizard to patch uglify-js@2.3.6.

Overview

uglify-js is a JavaScript parser, minifier, compressor and beautifier toolkit.

Tom MacWright discovered that UglifyJS versions 2.4.23 and earlier are affected by a vulnerability which allows a specially crafted Javascript file to have altered functionality after minification. This bug was demonstrated by Yan to allow potentially malicious code to be hidden within secure code, activated by minification.

Details

In Boolean algebra, DeMorgan's laws describe the relationships between conjunctions (&&), disjunctions (||) and negations (!). In Javascript form, they state that:

 !(a && b) === (!a) || (!b)
 !(a || b) === (!a) && (!b)

The law does not hold true when one of the values is not a boolean however.

Vulnerable versions of UglifyJS do not account for this restriction, and erroneously apply the laws to a statement if it can be reduced in length by it.

Consider this authentication function:

function isTokenValid(user) {
    var timeLeft =
        !!config && // config object exists
        !!user.token && // user object has a token
        !user.token.invalidated && // token is not explicitly invalidated
        !config.uninitialized && // config is initialized
        !config.ignoreTimestamps && // don't ignore timestamps
        getTimeLeft(user.token.expiry); // > 0 if expiration is in the future

    // The token must not be expired
    return timeLeft > 0;
}

function getTimeLeft(expiry) {
  return expiry - getSystemTime();
}

When minified with a vulnerable version of UglifyJS, it will produce the following insecure output, where a token will never expire:

( Formatted for readability )

function isTokenValid(user) {
    var timeLeft = !(                       // negation
        !config                             // config object does not exist
        || !user.token                      // user object does not have a token
        || user.token.invalidated           // token is explicitly invalidated
        || config.uninitialized             // config isn't initialized
        || config.ignoreTimestamps          // ignore timestamps
        || !getTimeLeft(user.token.expiry)  // > 0 if expiration is in the future
    );
    return timeLeft > 0
}

function getTimeLeft(expiry) {
    return expiry - getSystemTime()
}

Remediation

Upgrade UglifyJS to version 2.4.24 or higher.

References

high severity

Prototype Override Protection Bypass

  • Vulnerable module: qs
  • Introduced through: azure-mgmt-storage@0.9.16, falcor-router-demo@1.0.3 and others

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d azure-mgmt-storage@0.9.16 azure-common@0.9.11 request@2.45.0 qs@1.2.2
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d falcor-router-demo@1.0.3 pouchdb@3.6.0 request@2.28.0 qs@0.6.6
    Remediation: Upgrade to falcor-router-demo@1.0.5.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 qs@4.0.0
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 subtext@2.0.2 qs@5.2.1
    Remediation: Upgrade to hapi@11.0.4.

Overview

qs is a querystring parser that supports nesting and arrays, with a depth limit.

By default qs protects against attacks that attempt to overwrite an object's existing prototype properties, such as toString(), hasOwnProperty(),etc.

From qs documentation:

By default parameters that would overwrite properties on the object prototype are ignored, if you wish to keep the data from those fields either use plainObjects as mentioned above, or set allowPrototypes to true which will allow user input to overwrite those properties. WARNING It is generally a bad idea to enable this option as it can cause problems when attempting to use the properties that have been overwritten. Always be careful with this option.

Overwriting these properties can impact application logic, potentially allowing attackers to work around security controls, modify data, make the application unstable and more.

In versions of the package affected by this vulnerability, it is possible to circumvent this protection and overwrite prototype properties and functions by prefixing the name of the parameter with [ or ]. e.g. qs.parse("]=toString") will return {toString = true}, as a result, calling toString() on the object will throw an exception.

Example:

qs.parse('toString=foo', { allowPrototypes: false })
// {}

qs.parse("]=toString", { allowPrototypes: false })
// {toString = true} <== prototype overwritten

For more information, you can check out our blog.

Disclosure Timeline

  • February 13th, 2017 - Reported the issue to package owner.
  • February 13th, 2017 - Issue acknowledged by package owner.
  • February 16th, 2017 - Partial fix released in versions 6.0.3, 6.1.1, 6.2.2, 6.3.1.
  • March 6th, 2017 - Final fix released in versions 6.4.0,6.3.2, 6.2.3, 6.1.2 and 6.0.4

Remediation

Upgrade qs to version 6.4.0 or higher. Note: The fix was backported to the following versions 6.3.2, 6.2.3, 6.1.2, 6.0.4.

References

high severity

Regular Expression Denial of Service (DoS)

  • Vulnerable module: validator
  • Introduced through: azure-mgmt-storage@0.9.16

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d azure-mgmt-storage@0.9.16 azure-common@0.9.11 validator@3.1.0

Overview

validator is a library of string validators and sanitizers.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) attacks. It used a regular expression in order to validate URLs.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Update to version 3.22.1 or greater.

References

high severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: content
  • Introduced through: hapi@10.5.0

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 subtext@2.0.2 content@1.0.2
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 subtext@2.0.2 pez@1.0.0 content@1.0.2
    Remediation: Upgrade to hapi@11.0.4.

Overview

content is a HTTP Content-* headers parsing

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) attacks. An attacker may pass a specially crafted Content-Type or Content-Disposition header, causing the server to hang. This can cause an impact of about 10 seconds matching time for data 180 characters long.

Disclosure Timeline

  • Feb 5th, 2018 - Initial Disclosure to package owner
  • Feb 5th, 2018 - Initial Response from package owner
  • Feb 28th, 2018 - Fix issued
  • Mar 5th, 2018 - Vulnerability published

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade content to versions 3.0.7, 4.0.4 or higher

References

high severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: tough-cookie
  • Introduced through: falcor-router-demo@1.0.3

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d falcor-router-demo@1.0.3 pouchdb@3.6.0 request@2.28.0 tough-cookie@0.9.15
    Remediation: Upgrade to falcor-router-demo@1.0.5.

Overview

tough-cookie Hawk is an HTTP authentication scheme using a message authentication code (MAC) algorithm to provide partial HTTP request cryptographic verification.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) attacks. An attacker can provide a cookie, which nearly matches the pattern being matched. This will cause the regular expression matching to take a long time, all the while occupying the event loop and preventing it from processing other requests and making the server unavailable (a Denial of Service attack).

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade tough-cookie to at version 2.3.0 or greater.

References

medium severity

Arbitrary JavaScript Code Injection

  • Vulnerable module: bassmaster
  • Introduced through: bassmaster@1.5.1

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d bassmaster@1.5.1
    Remediation: Upgrade to bassmaster@1.5.2.

Overview

Old versions of bassmaster, a Hapi server plugin used to process batches of requests, use the eval method as part of its processing and validation of user input.

An attacker can therefore provide arbitrary javascript in this input, which will be executed by this eval function without limitation.

This is a very severe remote JavaScript code execution, and depending on the node process permissions can turn into Arbitrary Remote Code Execution on the operating system level as well.

Remediation

Update to bassmaster version 1.5.2 or greater.

References

medium severity

Buffer Overflow

  • Vulnerable module: validator
  • Introduced through: azure-mgmt-storage@0.9.16

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d azure-mgmt-storage@0.9.16 azure-common@0.9.11 validator@3.1.0

Overview

validator is a library of string validators and sanitizers.

Affected versions of this package are vulnerable to Buffer Overflow. It used a regular expression (/^(?:[A-Z0-9+\/]{4})*(?:[A-Z0-9+\/]{2}==|[A-Z0-9+\/]{3}=|[A-Z0-9+\/]{4})$/i) in order to validate Base64 strings.

Remediation

Upgrade validator to version 5.0.0 or higher.

References

medium severity

Cross-site Scripting (XSS)

  • Vulnerable module: handlebars
  • Introduced through: snyk-demo-child@0.0.1

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d snyk-demo-child@0.0.1 handlebars@3.0.3
    Remediation: Run snyk wizard to patch handlebars@3.0.3.

Overview

handlebars provides the power necessary to let you build semantic templates.

When using attributes without quotes in a handlebars template, an attacker can manipulate the input to introduce additional attributes, potentially executing code. This may lead to a Cross-site Scripting (XSS) vulnerability, assuming an attacker can influence the value entered into the template. If the handlebars template is used to render user-generated content, this vulnerability may escalate to a persistent XSS vulnerability.

Details

Cross-Site Scripting (XSS) attacks occur when an attacker tricks a user’s browser to execute malicious JavaScript code in the context of a victim’s domain. Such scripts can steal the user’s session cookies for the domain, scrape or modify its content, and perform or modify actions on the user’s behalf, actions typically blocked by the browser’s Same Origin Policy.

These attacks are possible by escaping the context of the web application and injecting malicious scripts in an otherwise trusted website. These scripts can introduce additional attributes (say, a "new" option in a dropdown list or a new link to a malicious site) and can potentially execute code on the clients side, unbeknown to the victim. This occurs when characters like < > " ' are not escaped properly.

There are a few types of XSS:

  • Persistent XSS is an attack in which the malicious code persists into the web app’s database.
  • Reflected XSS is an which the website echoes back a portion of the request. The attacker needs to trick the user into clicking a malicious link (for instance through a phishing email or malicious JS on another page), which triggers the XSS attack.
  • DOM-based XSS is an that occurs purely in the browser when client-side JavaScript echoes back a portion of the URL onto the page. DOM-Based XSS is notoriously hard to detect, as the server never gets a chance to see the attack taking place.

Example:

Assume handlebars was used to display user comments and avatar, using the following template: <img src={{avatarUrl}}><pre>{{comment}}</pre>

If an attacker spoofed their avatar URL and provided the following value: http://evil.org/avatar.png onload=alert(document.cookie)

The resulting HTML would be the following, triggering the script once the image loads: <img src=http://evil.org/avatar.png onload=alert(document.cookie)><pre>Gotcha!</pre>

References

medium severity

Cross-site Scripting (XSS)

  • Vulnerable module: validator
  • Introduced through: azure-mgmt-storage@0.9.16

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d azure-mgmt-storage@0.9.16 azure-common@0.9.11 validator@3.1.0

Overview

validator is a library of string validators and sanitizers.

Affected versions of this package are vulnerable to Cross-site Scripting (XSS) in IE9 due to unescaped backticks.

Details

Cross-Site Scripting (XSS) attacks occur when an attacker tricks a user’s browser to execute malicious JavaScript code in the context of a victim’s domain. Such scripts can steal the user’s session cookies for the domain, scrape or modify its content, and perform or modify actions on the user’s behalf, actions typically blocked by the browser’s Same Origin Policy.

These attacks are possible by escaping the context of the web application and injecting malicious scripts in an otherwise trusted website. These scripts can introduce additional attributes (say, a "new" option in a dropdown list or a new link to a malicious site) and can potentially execute code on the clients side, unbeknown to the victim. This occurs when characters like < > " ' are not escaped properly.

There are a few types of XSS:

  • Persistent XSS is an attack in which the malicious code persists into the web app’s database.
  • Reflected XSS is an which the website echoes back a portion of the request. The attacker needs to trick the user into clicking a malicious link (for instance through a phishing email or malicious JS on another page), which triggers the XSS attack.
  • DOM-based XSS is an that occurs purely in the browser when client-side JavaScript echoes back a portion of the URL onto the page. DOM-Based XSS is notoriously hard to detect, as the server never gets a chance to see the attack taking place.

Remediation

Upgrade validator to version 3.35.0 or higher.

References

medium severity

Denial of Service (Event Loop Blocking)

  • Vulnerable module: qs
  • Introduced through: falcor-router-demo@1.0.3

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d falcor-router-demo@1.0.3 pouchdb@3.6.0 request@2.28.0 qs@0.6.6
    Remediation: Upgrade to falcor-router-demo@1.0.5.

Overview

qs is a querystring parser that supports nesting and arrays, with a depth limit.

Affected versions of this package are vulnerable to Denial of Service (DoS). When parsing a string representing a deeply nested object, qs will block the event loop for long periods of time. Such a delay may hold up the server's resources, keeping it from processing other requests in the meantime, thus enabling a Denial-of-Service attack.

Remediation

Update qs to version 1.0.0 or higher. In these versions, qs enforces a max object depth (along with other limits), limiting the event loop length and thus preventing such an attack.

References

medium severity

Improper input validation

  • Vulnerable module: call
  • Introduced through: hapi@10.5.0

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 call@2.0.2
    Remediation: Upgrade to hapi@11.0.4.

Overview

call is the primary HTTP router of the hapi framework.

The vulnerability arise from undefined values inside a path (last segment being an exception) making their way into components that do not care for values being undefined (eg. the database layer).

For example, the request URI /delete/company// may incorrectly match a route looking for /delete/company/{company}/. By itself, the bad match is not a vulnerability. However, depending on the remaining logic in the application, such a bad match may result in skipping a protection mechanisms. In the above example, if the route translates to a DB delete command, it might delete all the companies from the db.

Remediation

Upgrade to version 3.0.2 or higher.

References

https://github.com/hapijs/hapi/issues/3228 https://github.com/hapijs/call/commit/9570eee5358b4383715cc6a13cb95971678efd30

medium severity

Insecure Randomness

  • Vulnerable module: cryptiles
  • Introduced through: azure-mgmt-storage@0.9.16, falcor-router-demo@1.0.3 and others

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d azure-mgmt-storage@0.9.16 azure-common@0.9.11 request@2.45.0 hawk@1.1.1 cryptiles@0.2.2
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d falcor-router-demo@1.0.3 pouchdb@3.6.0 request@2.28.0 hawk@1.0.0 cryptiles@0.2.2
    Remediation: Upgrade to falcor-router-demo@1.0.5.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 cryptiles@2.0.5
    Remediation: Upgrade to hapi@17.0.0.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 iron@2.1.3 cryptiles@2.0.5
    Remediation: Upgrade to hapi@17.0.0.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 statehood@2.1.1 cryptiles@2.0.5
    Remediation: Upgrade to hapi@17.0.0.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 statehood@2.1.1 iron@2.1.3 cryptiles@2.0.5
    Remediation: Upgrade to hapi@17.0.0.

Overview

cryptiles is a package for general crypto utilities.

Affected versions of this package are vulnerable to Insecure Randomness. The randomDigits() method is supposed to return a cryptographically strong pseudo-random data string, but it was biased to certain digits. An attacker could be able to guess the created digits.

Remediation

Upgrade to version 4.1.2 and higher.

References

medium severity

Regular Expression Denial of Service (DoS)

  • Vulnerable module: uglify-js
  • Introduced through: snyk-demo-child@0.0.1

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d snyk-demo-child@0.0.1 handlebars@3.0.3 uglify-js@2.3.6
    Remediation: Run snyk wizard to patch uglify-js@2.3.6.

Overview

The parse() function in the uglify-js package prior to version 2.6.0 is vulnerable to regular expression denial of service (ReDoS) attacks when long inputs of certain patterns are processed.

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade to version 2.6.0 or greater. If a direct dependency update is not possible, use snyk wizard to patch this vulnerability.

References

medium severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: content
  • Introduced through: hapi@10.5.0

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 subtext@2.0.2 content@1.0.2
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 subtext@2.0.2 pez@1.0.0 content@1.0.2
    Remediation: Upgrade to hapi@11.0.4.

Overview

content is HTTP Content-* headers parsing.

Affected versions of this package are vulnerable to Regular expression Denial of Service (ReDoS) attacks. An attacker may pass a specially crafted Content-Type or Content-Disposition header, causing the server to hang.

Details

<< ReDoS>>

Remediation

Upgrade content to version 3.0.6 or higher.

References

medium severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: semver
  • Introduced through: falcor-router-demo@1.0.3

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d falcor-router-demo@1.0.3 pouchdb@3.6.0 levelup@0.18.6 semver@2.3.2
    Remediation: Upgrade to falcor-router-demo@1.0.5.

Overview

npm is a package manager for javascript.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS). The semver module uses regular expressions when parsing a version string. For a carefully crafted input, the time it takes to process these regular expressions is not linear to the length of the input. Since the semver module did not enforce a limit on the version string length, an attacker could provide a long string that would take up a large amount of resources, potentially taking a server down. This issue therefore enables a potential Denial of Service attack. This is a slightly differnt variant of a typical Regular Expression Denial of Service (ReDoS) vulnerability.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Update to a version 4.3.2 or greater. From the issue description [2]: "Package version can no longer be more than 256 characters long. This prevents a situation in which parsing the version number can use exponentially more time and memory to parse, leading to a potential denial of service."

References

medium severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: tough-cookie
  • Introduced through: falcor-router-demo@1.0.3

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d falcor-router-demo@1.0.3 pouchdb@3.6.0 request@2.28.0 tough-cookie@0.9.15
    Remediation: Upgrade to falcor-router-demo@1.0.5.

Overview

tough-cookie is RFC6265 Cookies and Cookie Jar for node.js.

Affected versions of this package are vulnerable to Regular expression Denial of Service (ReDoS) attacks. An attacker may pass a specially crafted cookie, causing the server to hang.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade to version 2.3.3 or newer.

References

medium severity

Remote Memory Exposure

  • Vulnerable module: request
  • Introduced through: azure-mgmt-storage@0.9.16 and falcor-router-demo@1.0.3

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d azure-mgmt-storage@0.9.16 azure-common@0.9.11 request@2.45.0
    Remediation: Run snyk wizard to patch request@2.45.0.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d falcor-router-demo@1.0.3 pouchdb@3.6.0 request@2.28.0
    Remediation: Upgrade to falcor-router-demo@1.0.5.

Overview

request is a simplified http request client. A potential remote memory exposure vulnerability exists in request. If a request uses a multipart attachment and the body type option is number with value X, then X bytes of uninitialized memory will be sent in the body of the request.

Note that while the impact of this vulnerability is high (memory exposure), exploiting it is likely difficult, as the attacker needs to somehow control the body type of the request. One potential exploit scenario is when a request is composed based on JSON input, including the body type, allowing a malicious JSON to trigger the memory leak.

Details

Constructing a Buffer class with integer N creates a Buffer of length N with non zero-ed out memory. Example:

var x = new Buffer(100); // uninitialized Buffer of length 100
// vs
var x = new Buffer('100'); // initialized Buffer with value of '100'

Initializing a multipart body in such manner will cause uninitialized memory to be sent in the body of the request.

Proof of concept

var http = require('http')
var request = require('request')

http.createServer(function (req, res) {
  var data = ''
  req.setEncoding('utf8')
  req.on('data', function (chunk) {
    console.log('data')
    data += chunk
  })
  req.on('end', function () {
    // this will print uninitialized memory from the client
    console.log('Client sent:\n', data)
  })
  res.end()
}).listen(8000)

request({
  method: 'POST',
  uri: 'http://localhost:8000',
  multipart: [{ body: 1000 }]
},
function (err, res, body) {
  if (err) return console.error('upload failed:', err)
  console.log('sent')
})

Remediation

Upgrade request to version 2.68.0 or higher.

If a direct dependency update is not possible, use snyk wizard to patch this vulnerability.

References

medium severity

Timing Attack

  • Vulnerable module: http-signature
  • Introduced through: azure-mgmt-storage@0.9.16 and falcor-router-demo@1.0.3

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d azure-mgmt-storage@0.9.16 azure-common@0.9.11 request@2.45.0 http-signature@0.10.1
    Remediation: Run snyk wizard to patch http-signature@0.10.1.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d falcor-router-demo@1.0.3 pouchdb@3.6.0 request@2.28.0 http-signature@0.10.1
    Remediation: Upgrade to falcor-router-demo@1.0.5.

Overview

http-signature is a reference implementation of Joyent's HTTP Signature scheme.

Affected versions of the package are vulnerable to Timing Attacks due to time-variable comparison of signatures.

The library implemented a character to character comparison, similar to the built-in string comparison mechanism, ===, and not a time constant string comparison. As a result, the comparison will fail faster when the first characters in the signature are incorrect. An attacker can use this difference to perform a timing attack, essentially allowing them to guess the signature one character at a time.

You can read more about timing attacks in Node.js on the Snyk blog.

Remediation

Upgrade http-signature to version 1.0.0 or higher.

References

medium severity

Uninitialized Memory Exposure

  • Vulnerable module: bl
  • Introduced through: falcor-router-demo@1.0.3

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d falcor-router-demo@1.0.3 pouchdb@3.6.0 levelup@0.18.6 bl@0.8.2

Overview

bl is a storage object for collections of Node Buffers.

A possible memory disclosure vulnerability exists when a value of type number is provided to the append() method and results in concatenation of uninitialized memory to the buffer collection.

This is a result of unobstructed use of the Buffer constructor, whose insecure default constructor increases the odds of memory leakage.

Details

Constructing a Buffer class with integer N creates a Buffer of length N with raw (not "zero-ed") memory.

In the following example, the first call would allocate 100 bytes of memory, while the second example will allocate the memory needed for the string "100":

// uninitialized Buffer of length 100
x = new Buffer(100);
// initialized Buffer with value of '100'
x = new Buffer('100');

bl's append function uses the default Buffer constructor as-is, making it easy to append uninitialized memory to an existing list. If the value of the buffer list is exposed to users, it may expose raw server side memory, potentially holding secrets, private data and code. This is a similar vulnerability to the infamous Heartbleed flaw in OpenSSL.

const BufferList = require('bl')

var bl = new BufferList()
bl.append(new Buffer('abcd'))
bl.append(new Buffer('efg'))
bl.append('100')
// appends a Buffer holding 100 bytes of uninitialized memory
bl.append(100)                     
bl.append(new Buffer('j'))

You can read more about the insecure Buffer behavior on our blog.

Similar vulnerabilities were discovered in request, mongoose, ws and sequelize.

Note This is vulnerable only for Node <=4

References

low severity

CORS Bypass

  • Vulnerable module: hapi
  • Introduced through: hapi@10.5.0

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0
    Remediation: Upgrade to hapi@11.0.0.

Overview

Hapi v11.0.0 and below have an incorrect implementation of the CORS protocol, and allow for configurations that, at best, return inconsistent headers and, at worst, cross-origin activities that are expected to be forbidden.

Details

If the connection has CORS enabled but one route has it off, and the route is not GET, the OPTIONS prefetch request will return the default CORS headers and then the actual request will go through and return no CORS headers. This defeats the purpose of turning CORS on the route.

Remediation

Upgrade to a version 11.0.0 or greater.

References

low severity

Potentially loose security restrictions

  • Vulnerable module: hapi
  • Introduced through: hapi@10.5.0

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0
    Remediation: Upgrade to hapi@11.1.4.

Overview

Security restrictions (e.g. origin) get overridden by less restrictive defaults (i.e. all origins) in cases when server level, connection level or route level CORS configurations are combined.

References

low severity

Prototype Pollution

  • Vulnerable module: hoek
  • Introduced through: azure-mgmt-storage@0.9.16, falcor-router-demo@1.0.3 and others

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d azure-mgmt-storage@0.9.16 azure-common@0.9.11 request@2.45.0 hawk@1.1.1 hoek@0.9.1
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d falcor-router-demo@1.0.3 pouchdb@3.6.0 request@2.28.0 hawk@1.0.0 hoek@0.9.1
    Remediation: Upgrade to falcor-router-demo@1.0.5.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d azure-mgmt-storage@0.9.16 azure-common@0.9.11 request@2.45.0 hawk@1.1.1 boom@0.4.2 hoek@0.9.1
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d falcor-router-demo@1.0.3 pouchdb@3.6.0 request@2.28.0 hawk@1.0.0 boom@0.4.2 hoek@0.9.1
    Remediation: Upgrade to falcor-router-demo@1.0.5.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d azure-mgmt-storage@0.9.16 azure-common@0.9.11 request@2.45.0 hawk@1.1.1 sntp@0.2.4 hoek@0.9.1
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d falcor-router-demo@1.0.3 pouchdb@3.6.0 request@2.28.0 hawk@1.0.0 sntp@0.2.4 hoek@0.9.1
    Remediation: Upgrade to falcor-router-demo@1.0.5.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d azure-mgmt-storage@0.9.16 azure-common@0.9.11 request@2.45.0 hawk@1.1.1 cryptiles@0.2.2 boom@0.4.2 hoek@0.9.1
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d falcor-router-demo@1.0.3 pouchdb@3.6.0 request@2.28.0 hawk@1.0.0 cryptiles@0.2.2 boom@0.4.2 hoek@0.9.1
    Remediation: Upgrade to falcor-router-demo@1.0.5.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d inert@3.2.1 hoek@2.16.3
    Remediation: Upgrade to inert@4.0.0.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 hoek@2.16.3
    Remediation: Upgrade to hapi@13.4.0.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d bassmaster@1.5.1 hoek@2.16.3
    Remediation: Upgrade to bassmaster@2.0.0.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 subtext@2.0.2 hoek@2.16.3
    Remediation: Upgrade to hapi@12.0.0.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 statehood@2.1.1 hoek@2.16.3
    Remediation: Upgrade to hapi@13.0.0.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 shot@1.7.0 hoek@2.16.3
    Remediation: Upgrade to hapi@12.0.1.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 mimos@2.0.2 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 kilt@1.1.1 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 iron@2.1.3 hoek@2.16.3
    Remediation: Upgrade to hapi@13.0.0.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 heavy@3.0.1 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 catbox-memory@1.1.2 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 catbox@6.0.0 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 call@2.0.2 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d inert@3.2.1 ammo@1.0.1 hoek@2.16.3
    Remediation: Upgrade to inert@4.0.0.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 ammo@1.0.1 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 accept@1.1.0 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d inert@3.2.1 joi@6.10.1 hoek@2.16.3
    Remediation: Upgrade to inert@4.0.0.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 joi@6.10.1 hoek@2.16.3
    Remediation: Upgrade to hapi@13.1.0.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d falcor-hapi@netflix/falcor-hapi joi@6.10.1 hoek@2.16.3
    Remediation: Run snyk wizard to patch hoek@2.16.3.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d falcor-hapi@netflix/falcor-hapi boom@2.10.1 hoek@2.16.3
    Remediation: Run snyk wizard to patch hoek@2.16.3.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 boom@2.10.1 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d inert@3.2.1 boom@2.10.1 hoek@2.16.3
    Remediation: Upgrade to inert@4.0.0.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d bassmaster@1.5.1 boom@2.10.1 hoek@2.16.3
    Remediation: Upgrade to bassmaster@2.0.0.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 topo@1.1.0 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d falcor-hapi@netflix/falcor-hapi joi@6.10.1 topo@1.1.0 hoek@2.16.3
    Remediation: Run snyk wizard to patch hoek@2.16.3.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 accept@1.1.0 boom@2.10.1 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 ammo@1.0.1 boom@2.10.1 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 joi@6.10.1 topo@1.1.0 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d inert@3.2.1 joi@6.10.1 topo@1.1.0 hoek@2.16.3
    Remediation: Upgrade to inert@4.0.0.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 subtext@2.0.2 boom@2.10.1 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 subtext@2.0.2 wreck@6.3.0 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 catbox@6.0.0 joi@6.10.1 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 heavy@3.0.1 joi@6.10.1 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 statehood@2.1.1 joi@6.10.1 hoek@2.16.3
    Remediation: Upgrade to hapi@13.0.0.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 subtext@2.0.2 pez@1.0.0 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 subtext@2.0.2 content@1.0.2 hoek@2.16.3
    Remediation: Run snyk wizard to patch hoek@2.16.3.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d inert@3.2.1 ammo@1.0.1 boom@2.10.1 hoek@2.16.3
    Remediation: Upgrade to inert@4.0.0.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 statehood@2.1.1 boom@2.10.1 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 iron@2.1.3 boom@2.10.1 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 call@2.0.2 boom@2.10.1 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 heavy@3.0.1 boom@2.10.1 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 catbox@6.0.0 boom@2.10.1 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 statehood@2.1.1 iron@2.1.3 hoek@2.16.3
    Remediation: Upgrade to hapi@13.0.0.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 cryptiles@2.0.5 boom@2.10.1 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 statehood@2.1.1 cryptiles@2.0.5 boom@2.10.1 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 heavy@3.0.1 joi@6.10.1 topo@1.1.0 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 catbox@6.0.0 joi@6.10.1 topo@1.1.0 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 statehood@2.1.1 iron@2.1.3 boom@2.10.1 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 statehood@2.1.1 joi@6.10.1 topo@1.1.0 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 subtext@2.0.2 pez@1.0.0 content@1.0.2 hoek@2.16.3
    Remediation: Run snyk wizard to patch hoek@2.16.3.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 subtext@2.0.2 content@1.0.2 boom@2.10.1 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 iron@2.1.3 cryptiles@2.0.5 boom@2.10.1 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 subtext@2.0.2 wreck@6.3.0 boom@2.10.1 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 subtext@2.0.2 pez@1.0.0 nigel@1.0.1 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 subtext@2.0.2 pez@1.0.0 boom@2.10.1 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 subtext@2.0.2 pez@1.0.0 b64@2.0.1 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 subtext@2.0.2 pez@1.0.0 nigel@1.0.1 vise@1.0.0 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 subtext@2.0.2 pez@1.0.0 content@1.0.2 boom@2.10.1 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d hapi@10.5.0 statehood@2.1.1 iron@2.1.3 cryptiles@2.0.5 boom@2.10.1 hoek@2.16.3
    Remediation: Upgrade to hapi@11.0.4.

Overview

hoek is a Utility methods for the hapi ecosystem.

Affected versions of this package are vulnerable to Prototype Pollution. The utilities function allow modification of the Object prototype. If an attacker can control part of the structure passed to this function, they could add or modify an existing property.

PoC by Olivier Arteau (HoLyVieR)

var Hoek = require('hoek');
var malicious_payload = '{"__proto__":{"oops":"It works !"}}';

var a = {};
console.log("Before : " + a.oops);
Hoek.merge({}, JSON.parse(malicious_payload));
console.log("After : " + a.oops);

Remediation

Upgrade hoek to versions 4.2.1, 5.0.3 or higher.

References

low severity

Regular Expression Denial of Service (DoS)

  • Vulnerable module: hawk
  • Introduced through: azure-mgmt-storage@0.9.16 and falcor-router-demo@1.0.3

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d azure-mgmt-storage@0.9.16 azure-common@0.9.11 request@2.45.0 hawk@1.1.1
    Remediation: Run snyk wizard to patch hawk@1.1.1.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d falcor-router-demo@1.0.3 pouchdb@3.6.0 request@2.28.0 hawk@1.0.0
    Remediation: Upgrade to falcor-router-demo@1.0.5.

Overview

hawk is an HTTP authentication scheme using a message authentication code (MAC) algorithm to provide partial HTTP request cryptographic verification.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) attacks.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

You can read more about Regular Expression Denial of Service (ReDoS) on our blog.

References

low severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: mime
  • Introduced through: falcor-router-demo@1.0.3 and azure-mgmt-storage@0.9.16

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d falcor-router-demo@1.0.3 pouchdb@3.6.0 request@2.28.0 mime@1.2.11
    Remediation: Run snyk wizard to patch mime@1.2.11.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d azure-mgmt-storage@0.9.16 azure-common@0.9.11 request@2.45.0 form-data@0.1.4 mime@1.2.11
    Remediation: Run snyk wizard to patch mime@1.2.11.
  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d falcor-router-demo@1.0.3 pouchdb@3.6.0 request@2.28.0 form-data@0.1.4 mime@1.2.11
    Remediation: Run snyk wizard to patch mime@1.2.11.

Overview

mime is a comprehensive, compact MIME type module.

Affected versions of this package are vulnerable to Regular expression Denial of Service (ReDoS). It uses regex the following regex /.*[\.\/\\]/ in its lookup, which can cause a slowdown of 2 seconds for 50k characters.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Many Regular Expression implementations may reach extreme situations that cause them to work very slowly (exponentially related to input size), allowing an attacker to exploit this and can cause the program to enter these extreme situations by using a specially crafted input and cause the service to excessively consume CPU, resulting in a Denial of Service.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade mime to versions 1.4.1, 2.0.3 or higher.

References

low severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: validator
  • Introduced through: azure-mgmt-storage@0.9.16

Detailed paths

  • Introduced through: snyk-demo-app@snyk/snyk-demo-app#2f31650f3fbdfac424cb54708a66550e7a8e4e0d azure-mgmt-storage@0.9.16 azure-common@0.9.11 validator@3.1.0

Overview

validator is a library of string validators and sanitizers.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) attacks. It used a regular expression (^\s*data:([a-z]+\/[a-z0-9\-\+]+(;[a-z\-]+=[a-z0-9\-]+)?)?(;base64)?,[a-z0-9!\$&',\(\)\*\+,;=\-\._~:@\/\?%\s]*\s*$) in order to validate Data URIs. This can cause an impact of about 10 seconds matching time for data 70K characters long.

Disclosure Timeline

  • Feb 15th, 2018 - Initial Disclosure to package owner
  • Feb 16th, 2018 - Initial Response from package owner
  • Feb 18th, 2018 - Fix issued
  • Feb 18th, 2018 - Vulnerability published

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its original and legitimate users. There are many types of DoS attacks, ranging from trying to clog the network pipes to the system by generating a large volume of traffic from many machines (a Distributed Denial of Service - DDoS - attack) to sending crafted requests that cause a system to crash or take a disproportional amount of time to process.

The Regular expression Denial of Service (ReDoS) is a type of Denial of Service attack. Regular expressions are incredibly powerful, but they aren't very intuitive and can ultimately end up making it easy for attackers to take your site down.

Let’s take the following regular expression as an example:

regex = /A(B|C+)+D/

This regular expression accomplishes the following:

  • A The string must start with the letter 'A'
  • (B|C+)+ The string must then follow the letter A with either the letter 'B' or some number of occurrences of the letter 'C' (the + matches one or more times). The + at the end of this section states that we can look for one or more matches of this section.
  • D Finally, we ensure this section of the string ends with a 'D'

The expression would match inputs such as ABBD, ABCCCCD, ABCBCCCD and ACCCCCD

It most cases, it doesn't take very long for a regex engine to find a match:

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCD")'
0.04s user 0.01s system 95% cpu 0.052 total

$ time node -e '/A(B|C+)+D/.test("ACCCCCCCCCCCCCCCCCCCCCCCCCCCCX")'
1.79s user 0.02s system 99% cpu 1.812 total

The entire process of testing it against a 30 characters long string takes around ~52ms. But when given an invalid string, it takes nearly two seconds to complete the test, over ten times as long as it took to test a valid string. The dramatic difference is due to the way regular expressions get evaluated.

Most Regex engines will work very similarly (with minor differences). The engine will match the first possible way to accept the current character and proceed to the next one. If it then fails to match the next one, it will backtrack and see if there was another way to digest the previous character. If it goes too far down the rabbit hole only to find out the string doesn’t match in the end, and if many characters have multiple valid regex paths, the number of backtracking steps can become very large, resulting in what is known as catastrophic backtracking.

Let's look at how our expression runs into this problem, using a shorter string: "ACCCX". While it seems fairly straightforward, there are still four different ways that the engine could match those three C's:

  1. CCC
  2. CC+C
  3. C+CC
  4. C+C+C.

The engine has to try each of those combinations to see if any of them potentially match against the expression. When you combine that with the other steps the engine must take, we can use RegEx 101 debugger to see the engine has to take a total of 38 steps before it can determine the string doesn't match.

From there, the number of steps the engine must use to validate a string just continues to grow.

String Number of C's Number of steps
ACCCX 3 38
ACCCCX 4 71
ACCCCCX 5 136
ACCCCCCCCCCCCCCX 14 65,553

By the time the string includes 14 C's, the engine has to take over 65,000 steps just to see if the string is valid. These extreme situations can cause them to work very slowly (exponentially related to input size, as shown above), allowing an attacker to exploit this and can cause the service to excessively consume CPU, resulting in a Denial of Service.

Remediation

Upgrade validator to version 9.4.1 or higher.

References