scmobile@1.0.27

Vulnerabilities

11 via 27 paths

Dependencies

381

Source

npm

Find, fix and prevent vulnerabilities in your code.

Severity
  • 4
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Status
  • 11
  • 0
  • 0

high severity

Remote Memory Exposure

  • Vulnerable module: bl
  • Introduced through: npm-check-updates@2.15.0

Detailed paths

  • Introduced through: scmobile@1.0.27 npm-check-updates@2.15.0 npm@3.10.10 request@2.75.0 bl@1.1.2
    Remediation: Upgrade to npm-check-updates@3.0.0.
  • Introduced through: scmobile@1.0.27 npm-check-updates@2.15.0 npmi@2.0.1 npm@3.10.10 request@2.75.0 bl@1.1.2
    Remediation: Upgrade to npm-check-updates@3.0.0.

Overview

bl is a library that allows you to collect buffers and access with a standard readable buffer interface.

Affected versions of this package are vulnerable to Remote Memory Exposure. If user input ends up in consume() argument and can become negative, BufferList state can be corrupted, tricking it into exposing uninitialized memory via regular .slice() calls.

PoC by chalker

const { BufferList } = require('bl')
const secret = require('crypto').randomBytes(256)
for (let i = 0; i < 1e6; i++) {
  const clone = Buffer.from(secret)
  const bl = new BufferList()
  bl.append(Buffer.from('a'))
  bl.consume(-1024)
  const buf = bl.slice(1)
  if (buf.indexOf(clone) !== -1) {
    console.error(`Match (at ${i})`, buf)
  }
}

Remediation

Upgrade bl to version 2.2.1, 3.0.1, 4.0.3, 1.2.3 or higher.

References

high severity

Arbitrary File Overwrite

  • Vulnerable module: npm
  • Introduced through: npm-check-updates@2.15.0

Detailed paths

  • Introduced through: scmobile@1.0.27 npm-check-updates@2.15.0 npm@3.10.10
    Remediation: Upgrade to npm-check-updates@3.0.0.
  • Introduced through: scmobile@1.0.27 npm-check-updates@2.15.0 npmi@2.0.1 npm@3.10.10
    Remediation: Upgrade to npm-check-updates@3.0.0.

Overview

npm is a package manager for JavaScript.

Affected versions of this package are vulnerable to Arbitrary File Overwrite. It fails to prevent existing globally-installed binaries to be overwritten by other package installations. For example, if a package was installed globally and created a serve binary, any subsequent installs of packages that also create a serve binary would overwrite the first binary. This only affects files in /usr/local/bin.

For npm, this behaviour is still allowed in local installations and also through install scripts. This vulnerability bypasses a user using the --ignore-scripts install option.

Details

A Directory Traversal attack (also known as path traversal) aims to access files and directories that are stored outside the intended folder. By manipulating files with "dot-dot-slash (../)" sequences and its variations, or by using absolute file paths, it may be possible to access arbitrary files and directories stored on file system, including application source code, configuration, and other critical system files.

Directory Traversal vulnerabilities can be generally divided into two types:

  • Information Disclosure: Allows the attacker to gain information about the folder structure or read the contents of sensitive files on the system.

st is a module for serving static files on web pages, and contains a vulnerability of this type. In our example, we will serve files from the public route.

If an attacker requests the following URL from our server, it will in turn leak the sensitive private key of the root user.

curl http://localhost:8080/public/%2e%2e/%2e%2e/%2e%2e/%2e%2e/%2e%2e/root/.ssh/id_rsa

Note %2e is the URL encoded version of . (dot).

  • Writing arbitrary files: Allows the attacker to create or replace existing files. This type of vulnerability is also known as Zip-Slip.

One way to achieve this is by using a malicious zip archive that holds path traversal filenames. When each filename in the zip archive gets concatenated to the target extraction folder, without validation, the final path ends up outside of the target folder. If an executable or a configuration file is overwritten with a file containing malicious code, the problem can turn into an arbitrary code execution issue quite easily.

The following is an example of a zip archive with one benign file and one malicious file. Extracting the malicious file will result in traversing out of the target folder, ending up in /root/.ssh/ overwriting the authorized_keys file:

2018-04-15 22:04:29 .....           19           19  good.txt
2018-04-15 22:04:42 .....           20           20  ../../../../../../root/.ssh/authorized_keys

Remediation

Upgrade npm to version 6.13.4 or higher.

References

high severity

Arbitrary File Write

  • Vulnerable module: npm
  • Introduced through: npm-check-updates@2.15.0

Detailed paths

  • Introduced through: scmobile@1.0.27 npm-check-updates@2.15.0 npm@3.10.10
    Remediation: Upgrade to npm-check-updates@3.0.0.
  • Introduced through: scmobile@1.0.27 npm-check-updates@2.15.0 npmi@2.0.1 npm@3.10.10
    Remediation: Upgrade to npm-check-updates@3.0.0.

Overview

npm is a package manager for JavaScript.

Affected versions of this package are vulnerable to Arbitrary File Write. It fails to prevent access to folders outside of the intended node_modules folder through the bin field.

For npm, a properly constructed entry in the package.json bin field would allow a package publisher to modify and/or gain access to arbitrary files on a user’s system when the package is installed. This behaviour is possible through install scripts. This vulnerability bypasses a user using the --ignore-scripts install option.

Details

A Directory Traversal attack (also known as path traversal) aims to access files and directories that are stored outside the intended folder. By manipulating files with "dot-dot-slash (../)" sequences and its variations, or by using absolute file paths, it may be possible to access arbitrary files and directories stored on file system, including application source code, configuration, and other critical system files.

Directory Traversal vulnerabilities can be generally divided into two types:

  • Information Disclosure: Allows the attacker to gain information about the folder structure or read the contents of sensitive files on the system.

st is a module for serving static files on web pages, and contains a vulnerability of this type. In our example, we will serve files from the public route.

If an attacker requests the following URL from our server, it will in turn leak the sensitive private key of the root user.

curl http://localhost:8080/public/%2e%2e/%2e%2e/%2e%2e/%2e%2e/%2e%2e/root/.ssh/id_rsa

Note %2e is the URL encoded version of . (dot).

  • Writing arbitrary files: Allows the attacker to create or replace existing files. This type of vulnerability is also known as Zip-Slip.

One way to achieve this is by using a malicious zip archive that holds path traversal filenames. When each filename in the zip archive gets concatenated to the target extraction folder, without validation, the final path ends up outside of the target folder. If an executable or a configuration file is overwritten with a file containing malicious code, the problem can turn into an arbitrary code execution issue quite easily.

The following is an example of a zip archive with one benign file and one malicious file. Extracting the malicious file will result in traversing out of the target folder, ending up in /root/.ssh/ overwriting the authorized_keys file:

2018-04-15 22:04:29 .....           19           19  good.txt
2018-04-15 22:04:42 .....           20           20  ../../../../../../root/.ssh/authorized_keys

Remediation

Upgrade npm to version 6.13.3 or higher.

References

high severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: npm-user-validate
  • Introduced through: npm-check-updates@2.15.0

Detailed paths

  • Introduced through: scmobile@1.0.27 npm-check-updates@2.15.0 npm@3.10.10 npm-user-validate@0.1.5
    Remediation: Upgrade to npm-check-updates@3.0.0.
  • Introduced through: scmobile@1.0.27 npm-check-updates@2.15.0 npmi@2.0.1 npm@3.10.10 npm-user-validate@0.1.5
    Remediation: Upgrade to npm-check-updates@3.0.0.

Overview

npm-user-validate is an User validations for npm

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS). The regex that validates user emails took exponentially longer to process long input strings beginning with @ characters.

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 npm-user-validate to version 1.0.1 or higher.

References

medium severity

Time of Check Time of Use (TOCTOU)

  • Vulnerable module: chownr
  • Introduced through: npm-check-updates@2.15.0

Detailed paths

  • Introduced through: scmobile@1.0.27 npm-check-updates@2.15.0 npm@3.10.10 chownr@1.0.1
    Remediation: Upgrade to npm-check-updates@3.0.0.
  • Introduced through: scmobile@1.0.27 npm-check-updates@2.15.0 npmi@2.0.1 npm@3.10.10 chownr@1.0.1
    Remediation: Upgrade to npm-check-updates@3.0.0.

Overview

chownr is a package that takes the same arguments as fs.chown()

Affected versions of this package are vulnerable to Time of Check Time of Use (TOCTOU). Affected versions of this package are vulnerable toTime of Check Time of Use (TOCTOU) attacks.

It does not dereference symbolic links and changes the owner of the link, which can trick it into descending into unintended trees if a non-symlink is replaced by a symlink at a critical moment:

      fs.lstat(pathChild, function(er, stats) {
        if (er)
          return cb(er)
        if (!stats.isSymbolicLink())
          chownr(pathChild, uid, gid, then)

Remediation

Upgrade chownr to version 1.1.0 or higher.

References

medium severity

Prototype Pollution

  • Vulnerable module: hoek
  • Introduced through: npm-check-updates@2.15.0

Detailed paths

  • Introduced through: scmobile@1.0.27 npm-check-updates@2.15.0 npm@3.10.10 request@2.75.0 hawk@3.1.3 hoek@2.16.3
    Remediation: Upgrade to npm-check-updates@3.0.0.
  • Introduced through: scmobile@1.0.27 npm-check-updates@2.15.0 npm@3.10.10 request@2.75.0 hawk@3.1.3 boom@2.10.1 hoek@2.16.3
    Remediation: Upgrade to npm-check-updates@3.0.0.
  • Introduced through: scmobile@1.0.27 npm-check-updates@2.15.0 npm@3.10.10 request@2.75.0 hawk@3.1.3 sntp@1.0.9 hoek@2.16.3
    Remediation: Upgrade to npm-check-updates@3.0.0.
  • Introduced through: scmobile@1.0.27 npm-check-updates@2.15.0 npmi@2.0.1 npm@3.10.10 request@2.75.0 hawk@3.1.3 hoek@2.16.3
    Remediation: Upgrade to npm-check-updates@3.0.0.
  • Introduced through: scmobile@1.0.27 npm-check-updates@2.15.0 npm@3.10.10 request@2.75.0 hawk@3.1.3 cryptiles@2.0.5 boom@2.10.1 hoek@2.16.3
    Remediation: Upgrade to npm-check-updates@3.0.0.
  • Introduced through: scmobile@1.0.27 npm-check-updates@2.15.0 npmi@2.0.1 npm@3.10.10 request@2.75.0 hawk@3.1.3 boom@2.10.1 hoek@2.16.3
    Remediation: Upgrade to npm-check-updates@3.0.0.
  • Introduced through: scmobile@1.0.27 npm-check-updates@2.15.0 npmi@2.0.1 npm@3.10.10 request@2.75.0 hawk@3.1.3 sntp@1.0.9 hoek@2.16.3
    Remediation: Upgrade to npm-check-updates@3.0.0.
  • Introduced through: scmobile@1.0.27 npm-check-updates@2.15.0 npmi@2.0.1 npm@3.10.10 request@2.75.0 hawk@3.1.3 cryptiles@2.0.5 boom@2.10.1 hoek@2.16.3
    Remediation: Upgrade to npm-check-updates@3.0.0.

Overview

hoek is an 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);

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 hoek to version 4.2.1, 5.0.3 or higher.

References

medium severity

Access Restriction Bypass

  • Vulnerable module: npm
  • Introduced through: npm-check-updates@2.15.0

Detailed paths

  • Introduced through: scmobile@1.0.27 npm-check-updates@2.15.0 npm@3.10.10
    Remediation: Upgrade to npm-check-updates@3.0.0.
  • Introduced through: scmobile@1.0.27 npm-check-updates@2.15.0 npmi@2.0.1 npm@3.10.10
    Remediation: Upgrade to npm-check-updates@3.0.0.

Overview

npm is a package manager for JavaScript.

Affected versions of this package are vulnerable to Access Restriction Bypass. It might allow local users to bypass intended filesystem access restrictions due to ownerships of /etc and /usr directories are being changed unexpectedly, related to a "correctMkdir" issue.

Remediation

Upgrade npm to version 5.7.1 or higher.

References

medium severity

Insertion of Sensitive Information into Log File

  • Vulnerable module: npm
  • Introduced through: npm-check-updates@2.15.0

Detailed paths

  • Introduced through: scmobile@1.0.27 npm-check-updates@2.15.0 npm@3.10.10
    Remediation: Upgrade to npm-check-updates@3.0.0.
  • Introduced through: scmobile@1.0.27 npm-check-updates@2.15.0 npmi@2.0.1 npm@3.10.10
    Remediation: Upgrade to npm-check-updates@3.0.0.

Overview

npm is a package manager for JavaScript.

Affected versions of this package are vulnerable to Insertion of Sensitive Information into Log File. The CLI supports URLs like <protocol>://[<user>[:<password>]@]<hostname>[:<port>][:][/]<path>. The password value is not redacted and is printed to stdout and also to any generated log files.

Remediation

Upgrade npm to version 6.14.6 or higher.

References

medium severity

Uninitialized Memory Exposure

  • Vulnerable module: tunnel-agent
  • Introduced through: npm-check-updates@2.15.0

Detailed paths

  • Introduced through: scmobile@1.0.27 npm-check-updates@2.15.0 npm@3.10.10 request@2.75.0 tunnel-agent@0.4.3
    Remediation: Upgrade to npm-check-updates@3.0.0.
  • Introduced through: scmobile@1.0.27 npm-check-updates@2.15.0 npmi@2.0.1 npm@3.10.10 request@2.75.0 tunnel-agent@0.4.3
    Remediation: Upgrade to npm-check-updates@3.0.0.

Overview

tunnel-agent is HTTP proxy tunneling agent. Affected versions of the package are vulnerable to Uninitialized Memory Exposure.

A possible memory disclosure vulnerability exists when a value of type number is used to set the proxy.auth option of a request request and results in a possible uninitialized memory exposures in the request body.

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');

tunnel-agent's request construction 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.

Proof of concept by ChALkeR

require('request')({
  method: 'GET',
  uri: 'http://www.example.com',
  tunnel: true,
  proxy:{
      protocol: 'http:',
      host:"127.0.0.1",
      port:8080,
      auth:80
  }
});

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

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

Remediation

Upgrade tunnel-agent to version 0.6.0 or higher. Note This is vulnerable only for Node <=4

References

low severity

Unauthorized File Access

  • Vulnerable module: npm
  • Introduced through: npm-check-updates@2.15.0

Detailed paths

  • Introduced through: scmobile@1.0.27 npm-check-updates@2.15.0 npm@3.10.10
    Remediation: Upgrade to npm-check-updates@3.0.0.
  • Introduced through: scmobile@1.0.27 npm-check-updates@2.15.0 npmi@2.0.1 npm@3.10.10
    Remediation: Upgrade to npm-check-updates@3.0.0.

Overview

npm is a package manager for JavaScript.

Affected versions of this package are vulnerable to Unauthorized File Access. It is possible for packages to create symlinks to files outside of thenode_modules folder through the bin field upon installation.

For npm, a properly constructed entry in the package.json bin field would allow a package publisher to create a symlink pointing to arbitrary files on a user’s system when the package is installed. This behaviour is possible through install scripts. This vulnerability bypasses a user using the --ignore-scripts install option.

Remediation

Upgrade npm to version 6.13.3 or higher.

References

low severity

Command Injection

  • Vulnerable module: npm-programmatic
  • Introduced through: npm-programmatic@0.0.8

Detailed paths

  • Introduced through: scmobile@1.0.27 npm-programmatic@0.0.8

Overview

npm-programmatic is a library that allows you to access npm commands programmatically from javascript.

Affected versions of this package are vulnerable to Command Injection. The packages and option properties are concatenated together without any validation and are used by the exec function directly.

PoC

var root = require("npm-programmatic");
var attack_code = "& echo vulnerable > create.txt &";
root.install([attack_code], {"cwd": "./"});

Details

A cross-site scripting attack occurs when the attacker tricks a legitimate web-based application or site to accept a request as originating from a trusted source.

This is done by escaping the context of the web application; the web application then delivers that data to its users along with other trusted dynamic content, without validating it. The browser unknowingly executes malicious script on the client side (through client-side languages; usually JavaScript or HTML) in order to perform actions that are otherwise typically blocked by the browser’s Same Origin Policy.

ֿInjecting malicious code is the most prevalent manner by which XSS is exploited; for this reason, escaping characters in order to prevent this manipulation is the top method for securing code against this vulnerability.

Escaping means that the application is coded to mark key characters, and particularly key characters included in user input, to prevent those characters from being interpreted in a dangerous context. For example, in HTML, < can be coded as &lt; and > can be coded as &gt; in order to be interpreted and displayed as themselves in text, while within the code itself, they are used for HTML tags. If malicious content is injected into an application that escapes special characters and that malicious content uses < and > as HTML tags, those characters are nonetheless not interpreted as HTML tags by the browser if they’ve been correctly escaped in the application code and in this way the attempted attack is diverted.

The most prominent use of XSS is to steal cookies (source: OWASP HttpOnly) and hijack user sessions, but XSS exploits have been used to expose sensitive information, enable access to privileged services and functionality and deliver malware.

Types of attacks

There are a few methods by which XSS can be manipulated:

Type Origin Description
Stored Server The malicious code is inserted in the application (usually as a link) by the attacker. The code is activated every time a user clicks the link.
Reflected Server The attacker delivers a malicious link externally from the vulnerable web site application to a user. When clicked, malicious code is sent to the vulnerable web site, which reflects the attack back to the user’s browser.
DOM-based Client The attacker forces the user’s browser to render a malicious page. The data in the page itself delivers the cross-site scripting data.
Mutated The attacker injects code that appears safe, but is then rewritten and modified by the browser, while parsing the markup. An example is rebalancing unclosed quotation marks or even adding quotation marks to unquoted parameters.

Affected environments

The following environments are susceptible to an XSS attack:

  • Web servers
  • Application servers
  • Web application environments

How to prevent

This section describes the top best practices designed to specifically protect your code:

  • Sanitize data input in an HTTP request before reflecting it back, ensuring all data is validated, filtered or escaped before echoing anything back to the user, such as the values of query parameters during searches.
  • Convert special characters such as ?, &, /, <, > and spaces to their respective HTML or URL encoded equivalents.
  • Give users the option to disable client-side scripts.
  • Redirect invalid requests.
  • Detect simultaneous logins, including those from two separate IP addresses, and invalidate those sessions.
  • Use and enforce a Content Security Policy (source: Wikipedia) to disable any features that might be manipulated for an XSS attack.
  • Read the documentation for any of the libraries referenced in your code to understand which elements allow for embedded HTML.

Remediation

There is no fixed version for npm-programmatic.

References