Vulnerabilities

24 via 95 paths

Dependencies

220

Source

GitHub

Commit

0d8dfe6c

Find, fix and prevent vulnerabilities in your code.

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critical severity

Improper Input Validation

  • Vulnerable module: socket.io-parser
  • Introduced through: socket.io@1.7.3

Detailed paths

  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-parser@2.3.1
    Remediation: Upgrade to socket.io@2.2.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-adapter@0.5.0 socket.io-parser@2.3.1
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-client@1.7.3 socket.io-parser@2.3.1
    Remediation: Upgrade to socket.io@2.2.0.

Overview

socket.io-parser is a socket.io protocol parser

Affected versions of this package are vulnerable to Improper Input Validation. when parsing attachments containing untrusted user input. Attackers can overwrite the _placeholder object to place references to functions in query objects.

PoC

const decoder = new Decoder();

decoder.on("decoded", (packet) => {
  console.log(packet.data); // prints [ 'hello', [Function: splice] ]
})

decoder.add('51-["hello",{"_placeholder":true,"num":"splice"}]');
decoder.add(Buffer.from("world"));

Remediation

Upgrade socket.io-parser to version 3.3.3, 3.4.2, 4.0.5, 4.2.1 or higher.

References

high severity

Arbitrary Code Injection

  • Vulnerable module: xmlhttprequest-ssl
  • Introduced through: socket.io@1.7.3

Detailed paths

  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-client@1.7.3 engine.io-client@1.8.3 xmlhttprequest-ssl@1.5.3
    Remediation: Upgrade to socket.io@1.7.4.

Overview

xmlhttprequest-ssl is a fork of xmlhttprequest.

Affected versions of this package are vulnerable to Arbitrary Code Injection. Provided requests are sent synchronously (async=False on xhr.open), malicious user input flowing into xhr.send could result in arbitrary code being injected and run.

POC

const { XMLHttpRequest } = require("xmlhttprequest")

const xhr = new XMLHttpRequest()
xhr.open("POST", "http://localhost.invalid/", false /* use synchronize request */)
xhr.send("\\');require(\"fs\").writeFileSync(\"/tmp/aaaaa.txt\", \"poc-20210306\");req.end();//")

Remediation

Upgrade xmlhttprequest-ssl to version 1.6.2 or higher.

References

high severity

Denial of Service (DoS)

  • Vulnerable module: engine.io
  • Introduced through: socket.io@1.7.3

Detailed paths

  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 engine.io@1.8.3
    Remediation: Upgrade to socket.io@3.0.0.

Overview

engine.io is a realtime engine behind Socket.IO. It provides the foundation of a bidirectional connection between client and server

Affected versions of this package are vulnerable to Denial of Service (DoS) via a POST request to the long polling transport.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

  • High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

  • Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade engine.io to version 4.0.0 or higher.

References

high severity

Denial of Service (DoS)

  • Vulnerable module: engine.io
  • Introduced through: socket.io@1.7.3

Detailed paths

  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 engine.io@1.8.3
    Remediation: Upgrade to socket.io@2.5.0.

Overview

engine.io is a realtime engine behind Socket.IO. It provides the foundation of a bidirectional connection between client and server

Affected versions of this package are vulnerable to Denial of Service (DoS). A malicious client could send a specially crafted HTTP request, triggering an uncaught exception and killing the Node.js process.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

  • High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

  • Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade engine.io to version 3.6.1, 6.2.1 or higher.

References

high severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: fresh
  • Introduced through: express@5.0.0-alpha.5

Detailed paths

  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5 fresh@0.5.0
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5 send@0.15.1 fresh@0.5.0
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5 serve-static@1.12.1 send@0.15.1 fresh@0.5.0
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5 fresh@0.5.0
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5 send@0.15.1 fresh@0.5.0
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5 serve-static@1.12.1 send@0.15.1 fresh@0.5.0

Overview

fresh is HTTP response freshness testing.

Affected versions of this package are vulnerable to Regular expression Denial of Service (ReDoS) attacks. A Regular Expression (/ *, */) was used for parsing HTTP headers and take about 2 seconds matching time for 50k 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 fresh to version 0.5.2 or higher.

References

high severity

Directory Traversal

  • Vulnerable module: moment
  • Introduced through: moment@2.17.0

Detailed paths

  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 moment@2.17.0
    Remediation: Upgrade to moment@2.29.2.

Overview

moment is a lightweight JavaScript date library for parsing, validating, manipulating, and formatting dates.

Affected versions of this package are vulnerable to Directory Traversal when a user provides a locale string which is directly used to switch moment locale.

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 moment to version 2.29.2 or higher.

References

high severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: parsejson
  • Introduced through: socket.io@1.7.3

Detailed paths

  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-client@1.7.3 engine.io-client@1.8.3 parsejson@0.0.3
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-client@1.7.3 engine.io-client@1.8.3 parsejson@0.0.3

Overview

parsejson is a method that parses a JSON string and returns a JSON object.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) attacks. An attacker may pass a specially crafted JSON data, 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

There is no fixed version for parsejson.

References

high severity

Prototype Poisoning

  • Vulnerable module: qs
  • Introduced through: body-parser@1.17.1 and express@5.0.0-alpha.5

Detailed paths

  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 body-parser@1.17.1 qs@6.4.0
    Remediation: Upgrade to body-parser@1.19.2.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5 qs@6.4.0

Overview

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

Affected versions of this package are vulnerable to Prototype Poisoning which allows attackers to cause a Node process to hang, processing an Array object whose prototype has been replaced by one with an excessive length value.

Note: In many typical Express use cases, an unauthenticated remote attacker can place the attack payload in the query string of the URL that is used to visit the application, such as a[__proto__]=b&a[__proto__]&a[length]=100000000.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

  • High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

  • Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade qs to version 6.2.4, 6.3.3, 6.4.1, 6.5.3, 6.6.1, 6.7.3, 6.8.3, 6.9.7, 6.10.3 or higher.

References

high severity

Denial of Service (DoS)

  • Vulnerable module: socket.io-parser
  • Introduced through: socket.io@1.7.3

Detailed paths

  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-parser@2.3.1
    Remediation: Upgrade to socket.io@2.2.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-adapter@0.5.0 socket.io-parser@2.3.1
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-client@1.7.3 socket.io-parser@2.3.1
    Remediation: Upgrade to socket.io@2.2.0.

Overview

socket.io-parser is a socket.io protocol parser

Affected versions of this package are vulnerable to Denial of Service (DoS) via a large packet because a concatenation approach is used.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

  • High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

  • Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade socket.io-parser to version 3.3.2, 3.4.1 or higher.

References

high severity

Denial of Service (DoS)

  • Vulnerable module: ws
  • Introduced through: socket.io@1.7.3 and ws@2.2.0

Detailed paths

  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 engine.io@1.8.3 ws@1.1.2
    Remediation: Upgrade to socket.io@1.7.4.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-client@1.7.3 engine.io-client@1.8.3 ws@1.1.2
    Remediation: Upgrade to socket.io@1.7.4.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 ws@2.2.0
    Remediation: Upgrade to ws@3.3.1.

Overview

ws is a simple to use websocket client, server and console for node.js.

Affected versions of this package are vulnerable to Denial of Service (DoS) attacks. A specially crafted value of the Sec-WebSocket-Extensions header that used Object.prototype property names as extension or parameter names could be used to make a ws server crash.

PoC:

const WebSocket = require('ws');
const net = require('net');

const wss = new WebSocket.Server({ port: 3000 }, function () {
  const payload = 'constructor';  // or ',;constructor'

  const request = [
    'GET / HTTP/1.1',
    'Connection: Upgrade',
    'Sec-WebSocket-Key: test',
    'Sec-WebSocket-Version: 8',
    `Sec-WebSocket-Extensions: ${payload}`,
    'Upgrade: websocket',
    '\r\n'
  ].join('\r\n');

  const socket = net.connect(3000, function () {
    socket.resume();
    socket.write(request);
  });
});

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

  • High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

  • Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

Remediation

Upgrade ws to version 1.1.5, 3.3.1 or higher.

References

high severity

Directory Traversal

  • Vulnerable module: adm-zip
  • Introduced through: selenium-webdriver@3.3.0

Detailed paths

  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 selenium-webdriver@3.3.0 adm-zip@0.4.16
    Remediation: Upgrade to selenium-webdriver@3.5.0.

Overview

adm-zip is a JavaScript implementation for zip data compression for NodeJS.

Affected versions of this package are vulnerable to Directory Traversal. It could extract files outside the target folder.

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 adm-zip to version 0.5.2 or higher.

References

high severity

Access Restriction Bypass

  • Vulnerable module: xmlhttprequest-ssl
  • Introduced through: socket.io@1.7.3

Detailed paths

  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-client@1.7.3 engine.io-client@1.8.3 xmlhttprequest-ssl@1.5.3
    Remediation: Upgrade to socket.io@1.7.4.

Overview

xmlhttprequest-ssl is a fork of xmlhttprequest.

Affected versions of this package are vulnerable to Access Restriction Bypass. The package disables SSL certificate validation by default, because rejectUnauthorized (when the property exists but is undefined) is considered to be false within the https.request function of Node.js. In other words, no certificate is ever rejected.

PoC

const XMLHttpRequest = require('xmlhttprequest-ssl');

var xhr = new XMLHttpRequest();		/* pass empty object in version 1.5.4 to work around bug */

xhr.open("GET", "https://self-signed.badssl.com/");
xhr.addEventListener('readystatechange', () => console.log('ready state:', xhr.status));
xhr.addEventListener('loadend', loadend);

function loadend()
{
  console.log('loadend:', xhr);
  if (xhr.status === 0 && xhr.statusText.code === 'DEPTH_ZERO_SELF_SIGNED_CERT')
    console.log('test passed: self-signed cert rejected');
  else
    console.log('*** test failed: self-signed cert used to retrieve content');
}

xhr.send();

Remediation

Upgrade xmlhttprequest-ssl to version 1.6.1 or higher.

References

medium severity

Server-side Request Forgery (SSRF)

  • Vulnerable module: request
  • Introduced through: chromedriver@2.46.0

Detailed paths

  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 chromedriver@2.46.0 request@2.88.2

Overview

request is a simplified http request client.

Affected versions of this package are vulnerable to Server-side Request Forgery (SSRF) due to insufficient checks in the lib/redirect.js file by allowing insecure redirects in the default configuration, via an attacker-controller server that does a cross-protocol redirect (HTTP to HTTPS, or HTTPS to HTTP).

NOTE: request package has been deprecated, so a fix is not expected. See https://github.com/request/request/issues/3142.

Remediation

A fix was pushed into the master branch but not yet published.

References

medium severity

Prototype Pollution

  • Vulnerable module: tough-cookie
  • Introduced through: chromedriver@2.46.0

Detailed paths

  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 chromedriver@2.46.0 request@2.88.2 tough-cookie@2.5.0

Overview

tough-cookie is a RFC6265 Cookies and CookieJar module for Node.js.

Affected versions of this package are vulnerable to Prototype Pollution due to improper handling of Cookies when using CookieJar in rejectPublicSuffixes=false mode. Due to an issue with the manner in which the objects are initialized, an attacker can expose or modify a limited amount of property information on those objects. There is no impact to availability.

PoC

// PoC.js
async function main(){
var tough = require("tough-cookie");
var cookiejar = new tough.CookieJar(undefined,{rejectPublicSuffixes:false});
// Exploit cookie
await cookiejar.setCookie(
  "Slonser=polluted; Domain=__proto__; Path=/notauth",
  "https://__proto__/admin"
);
// normal cookie
var cookie = await cookiejar.setCookie(
  "Auth=Lol; Domain=google.com; Path=/notauth",
  "https://google.com/"
);

//Exploit cookie
var a = {};
console.log(a["/notauth"]["Slonser"])
}
main();

Details

Prototype Pollution is a vulnerability affecting JavaScript. Prototype Pollution refers to the ability to inject properties into existing JavaScript language construct prototypes, such as objects. JavaScript allows all Object attributes to be altered, including their magical attributes such as __proto__, constructor and prototype. An attacker manipulates these attributes to overwrite, or pollute, a JavaScript application object prototype of the base object by injecting other values. Properties on the Object.prototype are then inherited by all the JavaScript objects through the prototype chain. When that happens, this leads to either denial of service by triggering JavaScript exceptions, or it tampers with the application source code to force the code path that the attacker injects, thereby leading to remote code execution.

There are two main ways in which the pollution of prototypes occurs:

  • Unsafe Object recursive merge

  • Property definition by path

Unsafe Object recursive merge

The logic of a vulnerable recursive merge function follows the following high-level model:

merge (target, source)

  foreach property of source

    if property exists and is an object on both the target and the source

      merge(target[property], source[property])

    else

      target[property] = source[property]

When the source object contains a property named __proto__ defined with Object.defineProperty() , the condition that checks if the property exists and is an object on both the target and the source passes and the merge recurses with the target, being the prototype of Object and the source of Object as defined by the attacker. Properties are then copied on the Object prototype.

Clone operations are a special sub-class of unsafe recursive merges, which occur when a recursive merge is conducted on an empty object: merge({},source).

lodash and Hoek are examples of libraries susceptible to recursive merge attacks.

Property definition by path

There are a few JavaScript libraries that use an API to define property values on an object based on a given path. The function that is generally affected contains this signature: theFunction(object, path, value)

If the attacker can control the value of “path”, they can set this value to __proto__.myValue. myValue is then assigned to the prototype of the class of the object.

Types of attacks

There are a few methods by which Prototype Pollution can be manipulated:

Type Origin Short description
Denial of service (DoS) Client This is the most likely attack.
DoS occurs when Object holds generic functions that are implicitly called for various operations (for example, toString and valueOf).
The attacker pollutes Object.prototype.someattr and alters its state to an unexpected value such as Int or Object. In this case, the code fails and is likely to cause a denial of service.
For example: if an attacker pollutes Object.prototype.toString by defining it as an integer, if the codebase at any point was reliant on someobject.toString() it would fail.
Remote Code Execution Client Remote code execution is generally only possible in cases where the codebase evaluates a specific attribute of an object, and then executes that evaluation.
For example: eval(someobject.someattr). In this case, if the attacker pollutes Object.prototype.someattr they are likely to be able to leverage this in order to execute code.
Property Injection Client The attacker pollutes properties that the codebase relies on for their informative value, including security properties such as cookies or tokens.
For example: if a codebase checks privileges for someuser.isAdmin, then when the attacker pollutes Object.prototype.isAdmin and sets it to equal true, they can then achieve admin privileges.

Affected environments

The following environments are susceptible to a Prototype Pollution attack:

  • Application server

  • Web server

  • Web browser

How to prevent

  1. Freeze the prototype— use Object.freeze (Object.prototype).

  2. Require schema validation of JSON input.

  3. Avoid using unsafe recursive merge functions.

  4. Consider using objects without prototypes (for example, Object.create(null)), breaking the prototype chain and preventing pollution.

  5. As a best practice use Map instead of Object.

For more information on this vulnerability type:

Arteau, Oliver. “JavaScript prototype pollution attack in NodeJS application.” GitHub, 26 May 2018

Remediation

Upgrade tough-cookie to version 4.1.3 or higher.

References

medium severity

Missing Release of Resource after Effective Lifetime

  • Vulnerable module: inflight
  • Introduced through: selenium-webdriver@3.3.0 and chromedriver@2.46.0

Detailed paths

  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 selenium-webdriver@3.3.0 rimraf@2.7.1 glob@7.2.3 inflight@1.0.6
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 chromedriver@2.46.0 del@3.0.0 globby@6.1.0 glob@7.2.3 inflight@1.0.6
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 chromedriver@2.46.0 del@3.0.0 rimraf@2.7.1 glob@7.2.3 inflight@1.0.6

Overview

Affected versions of this package are vulnerable to Missing Release of Resource after Effective Lifetime via the makeres function due to improperly deleting keys from the reqs object after execution of callbacks. This behavior causes the keys to remain in the reqs object, which leads to resource exhaustion.

Exploiting this vulnerability results in crashing the node process or in the application crash.

Note: This library is not maintained, and currently, there is no fix for this issue. To overcome this vulnerability, several dependent packages have eliminated the use of this library.

To trigger the memory leak, an attacker would need to have the ability to execute or influence the asynchronous operations that use the inflight module within the application. This typically requires access to the internal workings of the server or application, which is not commonly exposed to remote users. Therefore, “Attack vector” is marked as “Local”.

PoC

const inflight = require('inflight');

function testInflight() {
  let i = 0;
  function scheduleNext() {
    let key = `key-${i++}`;
    const callback = () => {
    };
    for (let j = 0; j < 1000000; j++) {
      inflight(key, callback);
    }

    setImmediate(scheduleNext);
  }


  if (i % 100 === 0) {
    console.log(process.memoryUsage());
  }

  scheduleNext();
}

testInflight();

Remediation

There is no fixed version for inflight.

References

medium severity
new

Open Redirect

  • Vulnerable module: express
  • Introduced through: express@5.0.0-alpha.5

Detailed paths

  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5

Overview

express is a minimalist web framework.

Affected versions of this package are vulnerable to Open Redirect due to the implementation of URL encoding using encodeurl before passing it to the location header. This can lead to unexpected evaluations of malformed URLs by common redirect allow list implementations in applications, allowing an attacker to bypass a properly implemented allow list and redirect users to malicious sites.

Remediation

Upgrade express to version 4.19.2, 5.0.0-beta.3 or higher.

References

medium severity

Command Injection

  • Vulnerable module: chromedriver
  • Introduced through: chromedriver@2.46.0

Detailed paths

  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 chromedriver@2.46.0
    Remediation: Upgrade to chromedriver@119.0.1.

Overview

chromedriver is a ChromeDriver for Selenium

Affected versions of this package are vulnerable to Command Injection when setting the chromedriver.path to an arbitrary system binary. This could lead to unauthorized access and potentially malicious actions on the host system.

Note:

An attacker must have access to the system running the vulnerable chromedriver library to exploit it. The success of exploitation also depends on the permissions and privileges of the process running chromedriver.

Remediation

Upgrade chromedriver to version 119.0.1 or higher.

References

medium severity

Insecure Defaults

  • Vulnerable module: socket.io
  • Introduced through: socket.io@1.7.3

Detailed paths

  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3
    Remediation: Upgrade to socket.io@2.4.0.

Overview

socket.io is a node.js realtime framework server.

Affected versions of this package are vulnerable to Insecure Defaults due to CORS Misconfiguration. All domains are whitelisted by default.

Remediation

Upgrade socket.io to version 2.4.0 or higher.

References

medium severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: ws
  • Introduced through: socket.io@1.7.3 and ws@2.2.0

Detailed paths

  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 engine.io@1.8.3 ws@1.1.2
    Remediation: Upgrade to socket.io@2.3.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-client@1.7.3 engine.io-client@1.8.3 ws@1.1.2
    Remediation: Upgrade to socket.io@2.4.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 ws@2.2.0
    Remediation: Upgrade to ws@5.2.3.

Overview

ws is a simple to use websocket client, server and console for node.js.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS). A specially crafted value of the Sec-Websocket-Protocol header can be used to significantly slow down a ws server.

##PoC

for (const length of [1000, 2000, 4000, 8000, 16000, 32000]) {
  const value = 'b' + ' '.repeat(length) + 'x';
  const start = process.hrtime.bigint();

  value.trim().split(/ *, */);

  const end = process.hrtime.bigint();

  console.log('length = %d, time = %f ns', length, end - start);
}

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 ws to version 7.4.6, 6.2.2, 5.2.3 or higher.

References

medium severity

Prototype Pollution

  • Vulnerable module: xml2js
  • Introduced through: selenium-webdriver@3.3.0

Detailed paths

  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 selenium-webdriver@3.3.0 xml2js@0.4.23
    Remediation: Upgrade to selenium-webdriver@4.0.0.

Overview

Affected versions of this package are vulnerable to Prototype Pollution due to allowing an external attacker to edit or add new properties to an object. This is possible because the application does not properly validate incoming JSON keys, thus allowing the __proto__ property to be edited.

PoC

var parseString = require('xml2js').parseString;

let normal_user_request    = "<role>admin</role>";
let malicious_user_request = "<__proto__><role>admin</role></__proto__>";

const update_user = (userProp) => {
    // A user cannot alter his role. This way we prevent privilege escalations.
    parseString(userProp, function (err, user) {
        if(user.hasOwnProperty("role") && user?.role.toLowerCase() === "admin") {
            console.log("Unauthorized Action");
        } else {
            console.log(user?.role[0]);
        }
    });
}

update_user(normal_user_request);
update_user(malicious_user_request);

Details

Prototype Pollution is a vulnerability affecting JavaScript. Prototype Pollution refers to the ability to inject properties into existing JavaScript language construct prototypes, such as objects. JavaScript allows all Object attributes to be altered, including their magical attributes such as __proto__, constructor and prototype. An attacker manipulates these attributes to overwrite, or pollute, a JavaScript application object prototype of the base object by injecting other values. Properties on the Object.prototype are then inherited by all the JavaScript objects through the prototype chain. When that happens, this leads to either denial of service by triggering JavaScript exceptions, or it tampers with the application source code to force the code path that the attacker injects, thereby leading to remote code execution.

There are two main ways in which the pollution of prototypes occurs:

  • Unsafe Object recursive merge

  • Property definition by path

Unsafe Object recursive merge

The logic of a vulnerable recursive merge function follows the following high-level model:

merge (target, source)

  foreach property of source

    if property exists and is an object on both the target and the source

      merge(target[property], source[property])

    else

      target[property] = source[property]

When the source object contains a property named __proto__ defined with Object.defineProperty() , the condition that checks if the property exists and is an object on both the target and the source passes and the merge recurses with the target, being the prototype of Object and the source of Object as defined by the attacker. Properties are then copied on the Object prototype.

Clone operations are a special sub-class of unsafe recursive merges, which occur when a recursive merge is conducted on an empty object: merge({},source).

lodash and Hoek are examples of libraries susceptible to recursive merge attacks.

Property definition by path

There are a few JavaScript libraries that use an API to define property values on an object based on a given path. The function that is generally affected contains this signature: theFunction(object, path, value)

If the attacker can control the value of “path”, they can set this value to __proto__.myValue. myValue is then assigned to the prototype of the class of the object.

Types of attacks

There are a few methods by which Prototype Pollution can be manipulated:

Type Origin Short description
Denial of service (DoS) Client This is the most likely attack.
DoS occurs when Object holds generic functions that are implicitly called for various operations (for example, toString and valueOf).
The attacker pollutes Object.prototype.someattr and alters its state to an unexpected value such as Int or Object. In this case, the code fails and is likely to cause a denial of service.
For example: if an attacker pollutes Object.prototype.toString by defining it as an integer, if the codebase at any point was reliant on someobject.toString() it would fail.
Remote Code Execution Client Remote code execution is generally only possible in cases where the codebase evaluates a specific attribute of an object, and then executes that evaluation.
For example: eval(someobject.someattr). In this case, if the attacker pollutes Object.prototype.someattr they are likely to be able to leverage this in order to execute code.
Property Injection Client The attacker pollutes properties that the codebase relies on for their informative value, including security properties such as cookies or tokens.
For example: if a codebase checks privileges for someuser.isAdmin, then when the attacker pollutes Object.prototype.isAdmin and sets it to equal true, they can then achieve admin privileges.

Affected environments

The following environments are susceptible to a Prototype Pollution attack:

  • Application server

  • Web server

  • Web browser

How to prevent

  1. Freeze the prototype— use Object.freeze (Object.prototype).

  2. Require schema validation of JSON input.

  3. Avoid using unsafe recursive merge functions.

  4. Consider using objects without prototypes (for example, Object.create(null)), breaking the prototype chain and preventing pollution.

  5. As a best practice use Map instead of Object.

For more information on this vulnerability type:

Arteau, Oliver. “JavaScript prototype pollution attack in NodeJS application.” GitHub, 26 May 2018

Remediation

Upgrade xml2js to version 0.5.0 or higher.

References

low severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: debug
  • Introduced through: body-parser@1.17.1, express@5.0.0-alpha.5 and others

Detailed paths

  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 body-parser@1.17.1 debug@2.6.1
    Remediation: Upgrade to body-parser@1.18.2.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5 debug@2.6.1
    Remediation: Open PR to patch debug@2.6.1.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5 send@0.15.1 debug@2.6.1
    Remediation: Open PR to patch debug@2.6.1.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5 serve-static@1.12.1 send@0.15.1 debug@2.6.1
    Remediation: Open PR to patch debug@2.6.1.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 debug@2.3.3
    Remediation: Upgrade to socket.io@2.0.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 engine.io@1.8.3 debug@2.3.3
    Remediation: Upgrade to socket.io@2.0.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-adapter@0.5.0 debug@2.3.3
    Remediation: Upgrade to socket.io@2.0.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-client@1.7.3 debug@2.3.3
    Remediation: Upgrade to socket.io@2.0.2.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-client@1.7.3 engine.io-client@1.8.3 debug@2.3.3
    Remediation: Upgrade to socket.io@2.0.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-parser@2.3.1 debug@2.2.0
    Remediation: Upgrade to socket.io@2.0.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-adapter@0.5.0 socket.io-parser@2.3.1 debug@2.2.0
    Remediation: Open PR to patch debug@2.2.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-client@1.7.3 socket.io-parser@2.3.1 debug@2.2.0
    Remediation: Upgrade to socket.io@2.0.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 body-parser@1.17.1 debug@2.6.1
    Remediation: Upgrade to body-parser@1.18.2.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5 debug@2.6.1
    Remediation: Open PR to patch debug@2.6.1.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5 send@0.15.1 debug@2.6.1
    Remediation: Open PR to patch debug@2.6.1.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5 serve-static@1.12.1 send@0.15.1 debug@2.6.1
    Remediation: Open PR to patch debug@2.6.1.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 debug@2.3.3
    Remediation: Upgrade to socket.io@2.0.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 engine.io@1.8.3 debug@2.3.3
    Remediation: Upgrade to socket.io@2.0.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-adapter@0.5.0 debug@2.3.3
    Remediation: Upgrade to socket.io@2.0.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-client@1.7.3 debug@2.3.3
    Remediation: Upgrade to socket.io@2.0.2.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-client@1.7.3 engine.io-client@1.8.3 debug@2.3.3
    Remediation: Upgrade to socket.io@2.0.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-parser@2.3.1 debug@2.2.0
    Remediation: Upgrade to socket.io@2.0.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-adapter@0.5.0 socket.io-parser@2.3.1 debug@2.2.0
    Remediation: Open PR to patch debug@2.2.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-client@1.7.3 socket.io-parser@2.3.1 debug@2.2.0
    Remediation: Upgrade to socket.io@2.0.0.

Overview

debug is a small debugging utility.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) in the function useColors via manipulation of the str argument. The vulnerability can cause a very low impact of about 2 seconds of matching time for data 50k characters long.

Note: CVE-2017-20165 is a duplicate of this vulnerability.

PoC

Use the following regex in the %o formatter.

/\s*\n\s*/

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 debug to version 2.6.9, 3.1.0, 3.2.7, 4.3.1 or higher.

References

low severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: mime
  • Introduced through: express@5.0.0-alpha.5

Detailed paths

  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5 send@0.15.1 mime@1.3.4
    Remediation: Open PR to patch mime@1.3.4.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5 serve-static@1.12.1 send@0.15.1 mime@1.3.4
    Remediation: Open PR to patch mime@1.3.4.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5 send@0.15.1 mime@1.3.4
    Remediation: Open PR to patch mime@1.3.4.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5 serve-static@1.12.1 send@0.15.1 mime@1.3.4
    Remediation: Open PR to patch mime@1.3.4.

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.

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 version 1.4.1, 2.0.3 or higher.

References

low severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: moment
  • Introduced through: moment@2.17.0

Detailed paths

  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 moment@2.17.0
    Remediation: Upgrade to moment@2.19.3.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 moment@2.17.0
    Remediation: Upgrade to moment@2.19.3.

Overview

moment is a lightweight JavaScript date library for parsing, validating, manipulating, and formatting dates.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS). It used a regular expression (/[0-9]*['a-z\u00A0-\u05FF\u0700-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]+|[\u0600-\u06FF\/]+(\s*?[\u0600-\u06FF]+){1,2}/i) in order to parse dates specified as strings. This can cause a very low impact of about 2 seconds matching time for data 50k characters long.

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 moment to version 2.19.3 or higher.

References

low severity

Regular Expression Denial of Service (ReDoS)

  • Vulnerable module: ms
  • Introduced through: body-parser@1.17.1, express@5.0.0-alpha.5 and others

Detailed paths

  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 body-parser@1.17.1 debug@2.6.1 ms@0.7.2
    Remediation: Upgrade to body-parser@1.17.2.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5 debug@2.6.1 ms@0.7.2
    Remediation: Open PR to patch ms@0.7.2.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5 send@0.15.1 ms@0.7.2
    Remediation: Open PR to patch ms@0.7.2.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 debug@2.3.3 ms@0.7.2
    Remediation: Upgrade to socket.io@2.0.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5 send@0.15.1 debug@2.6.1 ms@0.7.2
    Remediation: Open PR to patch ms@0.7.2.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5 serve-static@1.12.1 send@0.15.1 ms@0.7.2
    Remediation: Open PR to patch ms@0.7.2.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 engine.io@1.8.3 debug@2.3.3 ms@0.7.2
    Remediation: Upgrade to socket.io@2.0.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-adapter@0.5.0 debug@2.3.3 ms@0.7.2
    Remediation: Upgrade to socket.io@2.0.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-client@1.7.3 debug@2.3.3 ms@0.7.2
    Remediation: Upgrade to socket.io@2.0.2.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5 serve-static@1.12.1 send@0.15.1 debug@2.6.1 ms@0.7.2
    Remediation: Open PR to patch ms@0.7.2.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-client@1.7.3 engine.io-client@1.8.3 debug@2.3.3 ms@0.7.2
    Remediation: Upgrade to socket.io@2.0.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-parser@2.3.1 debug@2.2.0 ms@0.7.1
    Remediation: Upgrade to socket.io@2.0.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-adapter@0.5.0 socket.io-parser@2.3.1 debug@2.2.0 ms@0.7.1
    Remediation: Open PR to patch ms@0.7.1.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-client@1.7.3 socket.io-parser@2.3.1 debug@2.2.0 ms@0.7.1
    Remediation: Upgrade to socket.io@2.0.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 body-parser@1.17.1 debug@2.6.1 ms@0.7.2
    Remediation: Upgrade to body-parser@1.17.2.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5 debug@2.6.1 ms@0.7.2
    Remediation: Open PR to patch ms@0.7.2.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5 send@0.15.1 ms@0.7.2
    Remediation: Open PR to patch ms@0.7.2.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 debug@2.3.3 ms@0.7.2
    Remediation: Upgrade to socket.io@2.0.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5 send@0.15.1 debug@2.6.1 ms@0.7.2
    Remediation: Open PR to patch ms@0.7.2.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5 serve-static@1.12.1 send@0.15.1 ms@0.7.2
    Remediation: Open PR to patch ms@0.7.2.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 engine.io@1.8.3 debug@2.3.3 ms@0.7.2
    Remediation: Upgrade to socket.io@2.0.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-adapter@0.5.0 debug@2.3.3 ms@0.7.2
    Remediation: Upgrade to socket.io@2.0.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-client@1.7.3 debug@2.3.3 ms@0.7.2
    Remediation: Upgrade to socket.io@2.0.2.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 express@5.0.0-alpha.5 serve-static@1.12.1 send@0.15.1 debug@2.6.1 ms@0.7.2
    Remediation: Open PR to patch ms@0.7.2.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-client@1.7.3 engine.io-client@1.8.3 debug@2.3.3 ms@0.7.2
    Remediation: Upgrade to socket.io@2.0.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-parser@2.3.1 debug@2.2.0 ms@0.7.1
    Remediation: Upgrade to socket.io@2.0.0.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-adapter@0.5.0 socket.io-parser@2.3.1 debug@2.2.0 ms@0.7.1
    Remediation: Open PR to patch ms@0.7.1.
  • Introduced through: wechaty@Chatie/wechaty#0d8dfe6c65663bfbd9048c60abeca8bf3b64ef01 socket.io@1.7.3 socket.io-client@1.7.3 socket.io-parser@2.3.1 debug@2.2.0 ms@0.7.1
    Remediation: Upgrade to socket.io@2.0.0.

Overview

ms is a tiny millisecond conversion utility.

Affected versions of this package are vulnerable to Regular Expression Denial of Service (ReDoS) due to an incomplete fix for previously reported vulnerability npm:ms:20151024. The fix limited the length of accepted input string to 10,000 characters, and turned to be insufficient making it possible to block the event loop for 0.3 seconds (on a typical laptop) with a specially crafted string passed to ms() function.

Proof of concept

ms = require('ms');
ms('1'.repeat(9998) + 'Q') // Takes about ~0.3s

Note: Snyk's patch for this vulnerability limits input length to 100 characters. This new limit was deemed to be a breaking change by the author. Based on user feedback, we believe the risk of breakage is very low, while the value to your security is much greater, and therefore opted to still capture this change in a patch for earlier versions as well. Whenever patching security issues, we always suggest to run tests on your code to validate that nothing has been broken.

For more information on Regular Expression Denial of Service (ReDoS) attacks, go to our blog.

Disclosure Timeline

  • Feb 9th, 2017 - Reported the issue to package owner.
  • Feb 11th, 2017 - Issue acknowledged by package owner.
  • April 12th, 2017 - Fix PR opened by Snyk Security Team.
  • May 15th, 2017 - Vulnerability published.
  • May 16th, 2017 - Issue fixed and version 2.0.0 released.
  • May 21th, 2017 - Patches released for versions >=0.7.1, <=1.0.0.

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 ms to version 2.0.0 or higher.

References