exsilium/mungit

Git made easy, a fork of ungit.

Vulnerabilities

9 via 17 paths

Dependencies

618

Source

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Severity
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Status
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high severity

Arbitrary File Overwrite

  • Vulnerable module: npm
  • Introduced through: npm@6.5.0

Detailed paths

  • Introduced through: mungit@exsilium/mungit npm@6.5.0
    Remediation: Upgrade to npm@6.13.4.

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@6.5.0

Detailed paths

  • Introduced through: mungit@exsilium/mungit npm@6.5.0
    Remediation: Upgrade to npm@6.13.3.

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

medium severity

Denial of Service (DoS)

  • Vulnerable module: mem
  • Introduced through: npm@6.5.0

Detailed paths

  • Introduced through: mungit@exsilium/mungit npm@6.5.0 lock-verify@2.2.0 @iarna/cli@1.2.0 yargs@8.0.2 os-locale@2.1.0 mem@1.1.0
  • Introduced through: mungit@exsilium/mungit npm@6.5.0 libcipm@2.0.2 lock-verify@2.2.0 @iarna/cli@1.2.0 yargs@8.0.2 os-locale@2.1.0 mem@1.1.0

Overview

mem is an optimization used to speed up consecutive function calls by caching the result of calls with identical input.

Affected versions of this package are vulnerable to Denial of Service (DoS). Old results were deleted from the cache and could cause a memory leak.

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 mem to version 4.0.0 or higher.

References

medium severity

new

Insertion of Sensitive Information into Log File

  • Vulnerable module: npm
  • Introduced through: npm@6.5.0

Detailed paths

  • Introduced through: mungit@exsilium/mungit npm@6.5.0
    Remediation: Upgrade to npm@6.14.6.

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

new

Insertion of Sensitive Information into Log File

  • Vulnerable module: npm-registry-fetch
  • Introduced through: npm@6.5.0

Detailed paths

  • Introduced through: mungit@exsilium/mungit npm@6.5.0 libnpmhook@4.0.1 npm-registry-fetch@3.9.1
    Remediation: Upgrade to npm@6.6.0.
  • Introduced through: mungit@exsilium/mungit npm@6.5.0 npm-registry-fetch@1.1.1
    Remediation: Upgrade to npm@6.10.2.

Overview

npm-registry-fetch is a Fetch-based http client for use with npm registry APIs

Affected versions of this package are vulnerable to Insertion of Sensitive Information into Log File through log files. The package 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-registry-fetch to version 4.0.5, 8.1.1 or higher.

References

medium severity

Prototype Pollution

  • Vulnerable module: dot-prop
  • Introduced through: npm@6.5.0

Detailed paths

  • Introduced through: mungit@exsilium/mungit npm@6.5.0 update-notifier@2.5.0 configstore@3.1.2 dot-prop@4.2.0
  • Introduced through: mungit@exsilium/mungit npm@6.5.0 libnpx@10.2.3 update-notifier@2.5.0 configstore@3.1.2 dot-prop@4.2.0
  • Introduced through: mungit@exsilium/mungit npm@6.5.0 lock-verify@2.2.0 @iarna/cli@1.2.0 update-notifier@2.5.0 configstore@3.1.2 dot-prop@4.2.0
  • Introduced through: mungit@exsilium/mungit npm@6.5.0 libcipm@2.0.2 lock-verify@2.2.0 @iarna/cli@1.2.0 update-notifier@2.5.0 configstore@3.1.2 dot-prop@4.2.0

Overview

dot-prop is a package to get, set, or delete a property from a nested object using a dot path.

Affected versions of this package are vulnerable to Prototype Pollution. It is possible for a user to modify the prototype of a base object.

PoC by aaron_costello

var dotProp = require("dot-prop")
const object = {};
console.log("Before " + object.b); //Undefined
dotProp.set(object, '__proto__.b', true);
console.log("After " + {}.b); //true

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 dot-prop to version 5.1.1 or higher.

References

medium severity

Prototype Pollution

  • Vulnerable module: yargs-parser
  • Introduced through: npm@6.5.0 and yargs@12.0.5

Detailed paths

  • Introduced through: mungit@exsilium/mungit npm@6.5.0 lock-verify@2.2.0 @iarna/cli@1.2.0 yargs@8.0.2 yargs-parser@7.0.0
  • Introduced through: mungit@exsilium/mungit npm@6.5.0 libcipm@2.0.2 lock-verify@2.2.0 @iarna/cli@1.2.0 yargs@8.0.2 yargs-parser@7.0.0
  • Introduced through: mungit@exsilium/mungit npm@6.5.0 libnpx@10.2.3 yargs@11.1.1 yargs-parser@9.0.2
  • Introduced through: mungit@exsilium/mungit yargs@12.0.5 yargs-parser@11.1.1
    Remediation: Upgrade to yargs@13.1.0.

Overview

yargs-parser is a mighty option parser used by yargs.

Affected versions of this package are vulnerable to Prototype Pollution. The library could be tricked into adding or modifying properties of Object.prototype using a __proto__ payload.

Our research team checked several attack vectors to verify this vulnerability:

  1. It could be used for privilege escalation.
  2. The library could be used to parse user input received from different sources:
    • terminal emulators
    • system calls from other code bases
    • CLI RPC servers

PoC by Snyk

const parser = require("yargs-parser");
console.log(parser('--foo.__proto__.bar baz'));
console.log(({}).bar);

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 yargs-parser to version 5.0.0-security.0, 13.1.2, 15.0.1, 18.1.1 or higher.

References

medium severity

Time of Check Time of Use (TOCTOU)

  • Vulnerable module: chownr
  • Introduced through: npm@6.5.0

Detailed paths

  • Introduced through: mungit@exsilium/mungit npm@6.5.0 chownr@1.0.1
    Remediation: Upgrade to npm@6.6.0.

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

low severity

Unauthorized File Access

  • Vulnerable module: npm
  • Introduced through: npm@6.5.0

Detailed paths

  • Introduced through: mungit@exsilium/mungit npm@6.5.0
    Remediation: Upgrade to npm@6.13.3.

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