CVE-2022-31180

Shescape is a simple shell escape package for JavaScript. Affected versions were found to have insufficient escaping of white space when interpolating output. This issue only impacts users that use the escape or escapeAll functions with the interpolation option set to true. The result is that if an attacker is able to include whitespace in their input they can: 1. Invoke shell-specific behaviour through shell-specific special characters inserted directly after whitespace. 2. Invoke shell-specific behaviour through shell-specific special characters inserted or appearing after line terminating characters. 3. Invoke arbitrary commands by inserting a line feed character. 4. Invoke arbitrary commands by inserting a carriage return character. Behaviour number 1 has been patched in [v1.5.7] which you can upgrade to now. No further changes are required. Behaviour number 2, 3, and 4 have been patched in [v1.5.8] which you can upgrade to now. No further changes are required. The best workaround is to avoid having to use the interpolation: true option - in most cases using an alternative is possible, see the recipes for recommendations. Alternatively, users may strip all whitespace from user input. Note that this is error prone, for example: for PowerShell this requires stripping '\u0085' which is not included in JavaScript's definition of \s for Regular Expressions.

Shescape is a simple shell escape package for JavaScript. Affected versions were found to have insufficient escaping of white space when interpolating output. This issue only impacts users that use the escape or escapeAll functions with the interpolation option set to true. The result is that if an attacker is able to include whitespace in their input they can: 1. Invoke shell-specific behaviour through shell-specific special characters inserted directly after whitespace. 2. Invoke shell-specific behaviour through shell-specific special characters inserted or appearing after line terminating characters. 3. Invoke arbitrary commands by inserting a line feed character. 4. Invoke arbitrary commands by inserting a carriage return character. Behaviour number 1 has been patched in [v1.5.7] which you can upgrade to now. No further changes are required. Behaviour number 2, 3, and 4 have been patched in [v1.5.8] which you can upgrade to now. No further changes are required. The best workaround is to avoid having to use the interpolation: true option - in most cases using an alternative is possible, see the recipes for recommendations. Alternatively, users may strip all whitespace from user input. Note that this is error prone, for example: for PowerShell this requires stripping '\u0085' which is not included in JavaScript's definition of \s for Regular Expressions.

Impact

This only impacts users that use the escape or escapeAll functions with the interpolation option set to true. Example:

import cp from "node:child_process";
import * as shescape from "shescape";

// 1. Prerequisites
const options = {
  shell: "bash",
  // Or
  shell: "dash",
  // Or
  shell: "powershell.exe",
  // Or
  shell: "zsh",
  // Or
  shell: undefined, // Only if the default shell is one of the affected shells.
};

// 2. Attack (one of multiple)
const payload = "foo #bar";

// 3. Usage
let escapedPayload;
shescape.escape(payload, { interpolation: true });
// Or
shescape.escapeAll(payload, { interpolation: true });

cp.execSync(`echo Hello ${escapedPayload}!`, options);
// _Output depends on the shell being used_

The result is that if an attacker is able to include whitespace in their input they can:

1. Invoke shell-specific behaviour through shell-specific special characters inserted directly after whitespace.
   • Affected shells: Bash, Dash, Zsh, PowerShell
2. Invoke shell-specific behaviour through shell-specific special characters inserted or appearing after line terminating characters.
   • Affected shells: Bash
3. Invoke arbitrary commands by inserting a line feed character.
   • Affected Shells: Bash, Dash, Zsh, PowerShell
4. Invoke arbitrary commands by inserting a carriage return character.
   • Affected Shells: PowerShell

Patches

Behaviour number 1 has been patched in v1.5.7 which you can upgrade to now. No further changes are required.

Behaviour number 2, 3, and 4 have been patched in v1.5.8 which you can upgrade to now. No further changes are required.

Workarounds

The best workaround is to avoid having to use the interpolation: true option - in most cases using an alternative is possible, see the recipes for recommendations.

Alternatively, you can strip all whitespace from user input. Note that this is error prone, for example: for PowerShell this requires stripping '\u0085' which is not included in JavaScript's definition of \s for Regular Expressions.

References

• https://github.com/ericcornelissen/shescape/pull/322
• https://github.com/ericcornelissen/shescape/pull/324
• https://github.com/ericcornelissen/shescape/pull/332
• https://github.com/ericcornelissen/shescape/releases/tag/v1.5.7
• https://github.com/ericcornelissen/shescape/releases/tag/v1.5.8

For more information

• Comment on:
  • For behaviour 1 (PowerShell): https://github.com/ericcornelissen/shescape/pull/322
  • For behaviour 1 (Bash, Dash, Zsh): https://github.com/ericcornelissen/shescape/pull/324
  • For behaviour 2, 3, 4 (any shell): https://github.com/ericcornelissen/shescape/pull/332
• Open an issue at https://github.com/ericcornelissen/shescape/issues (New issue > Question > Get started)
• If you're missing CMD from this advisory, see https://github.com/ericcornelissen/shescape/security/advisories/GHSA-jjc5-fp7p-6f8w

Shescape is a simple shell escape package for JavaScript. Affected versions were found to have insufficient escaping of white space when interpolating output. This issue only impacts users that use the escape or escapeAll functions with the interpolation option set to true. The result is that if an attacker is able to include whitespace in their input they can: 1. Invoke shell-specific behaviour through shell-specific special characters inserted directly after whitespace. 2. Invoke shell-specific behaviour through shell-specific special characters inserted or appearing after line terminating characters. 3. Invoke arbitrary commands by inserting a line feed character. 4. Invoke arbitrary commands by inserting a carriage return character. Behaviour number 1 has been patched in [v1.5.7] which you can upgrade to now. No further changes are required. Behaviour number 2, 3, and 4 have been patched in [v1.5.8] which you can upgrade to now. No further changes are required. The best workaround is to avoid having to use the interpolation: true option - in most cases using an alternative is possible, see the recipes for recommendations. Alternatively, users may strip all whitespace from user input. Note that this is error prone, for example: for PowerShell this requires stripping '\u0085' which is not included in JavaScript's definition of \s for Regular Expressions.

Shescape is a simple shell escape package for JavaScript. Affected versions were found to have insufficient escaping of white space when interpolating output. This issue only impacts users that use the escape or escapeAll functions with the interpolation option set to true. The result is that if an attacker is able to include whitespace in their input they can: 1. Invoke shell-specific behaviour through shell-specific special characters inserted directly after whitespace. 2. Invoke shell-specific behaviour through shell-specific special characters inserted or appearing after line terminating characters. 3. Invoke arbitrary commands by inserting a line feed character. 4. Invoke arbitrary commands by inserting a carriage return character. Behaviour number 1 has been patched in [v1.5.7] which you can upgrade to now. No further changes are required. Behaviour number 2, 3, and 4 have been patched in [v1.5.8] which you can upgrade to now. No further changes are required. The best workaround is to avoid having to use the interpolation: true option - in most cases using an alternative is possible, see the recipes for recommendations. Alternatively, users may strip all whitespace from user input. Note that this is error prone, for example: for PowerShell this requires stripping '\u0085' which is not included in JavaScript's definition of \s for Regular Expressions.

Impact

This only impacts users that use the escape or escapeAll functions with the interpolation option set to true. Example:

import cp from "node:child_process";
import * as shescape from "shescape";

// 1. Prerequisites
const options = {
  shell: "bash",
  // Or
  shell: "dash",
  // Or
  shell: "powershell.exe",
  // Or
  shell: "zsh",
  // Or
  shell: undefined, // Only if the default shell is one of the affected shells.
};

// 2. Attack (one of multiple)
const payload = "foo #bar";

// 3. Usage
let escapedPayload;
shescape.escape(payload, { interpolation: true });
// Or
shescape.escapeAll(payload, { interpolation: true });

cp.execSync(`echo Hello ${escapedPayload}!`, options);
// _Output depends on the shell being used_

The result is that if an attacker is able to include whitespace in their input they can:

1. Invoke shell-specific behaviour through shell-specific special characters inserted directly after whitespace.
   • Affected shells: Bash, Dash, Zsh, PowerShell
2. Invoke shell-specific behaviour through shell-specific special characters inserted or appearing after line terminating characters.
   • Affected shells: Bash
3. Invoke arbitrary commands by inserting a line feed character.
   • Affected Shells: Bash, Dash, Zsh, PowerShell
4. Invoke arbitrary commands by inserting a carriage return character.
   • Affected Shells: PowerShell

Patches

Behaviour number 1 has been patched in v1.5.7 which you can upgrade to now. No further changes are required.

Behaviour number 2, 3, and 4 have been patched in v1.5.8 which you can upgrade to now. No further changes are required.

Workarounds

The best workaround is to avoid having to use the interpolation: true option - in most cases using an alternative is possible, see the recipes for recommendations.

Alternatively, you can strip all whitespace from user input. Note that this is error prone, for example: for PowerShell this requires stripping '\u0085' which is not included in JavaScript's definition of \s for Regular Expressions.

References

• https://github.com/ericcornelissen/shescape/pull/322
• https://github.com/ericcornelissen/shescape/pull/324
• https://github.com/ericcornelissen/shescape/pull/332
• https://github.com/ericcornelissen/shescape/releases/tag/v1.5.7
• https://github.com/ericcornelissen/shescape/releases/tag/v1.5.8

For more information

• Comment on:
  • For behaviour 1 (PowerShell): https://github.com/ericcornelissen/shescape/pull/322
  • For behaviour 1 (Bash, Dash, Zsh): https://github.com/ericcornelissen/shescape/pull/324
  • For behaviour 2, 3, 4 (any shell): https://github.com/ericcornelissen/shescape/pull/332
• Open an issue at https://github.com/ericcornelissen/shescape/issues (New issue > Question > Get started)
• If you're missing CMD from this advisory, see https://github.com/ericcornelissen/shescape/security/advisories/GHSA-jjc5-fp7p-6f8w