Headline

GHSA-j55r-787p-m549: Shescape on Windows escaping may be bypassed in threaded context

Impact

This may impact users that use Shescape on Windows in a threaded context (e.g. using Worker threads). The vulnerability can result in Shescape escaping (or quoting) for the wrong shell, thus allowing attackers to bypass protections depending on the combination of expected and used shell.

This snippet demonstrates a vulnerable use of Shescape:

// vulnerable.js

import { exec } from "node:child_process";
import { Worker, isMainThread } from 'node:worker_threads';

import * as shescape from "shescape";

if (isMainThread) {
  // 1. Something like a worker thread must be used. The reason being that they
  // unexpectedly change environment variable names on Windows.
  new Worker("./vulnerable.js");
} else {
  // 2. Example configuration that's problematic. In this setup example the
  // expected default system shell is CMD. We configure the use of PowerShell.
  // Shescape will fail to look up PowerShell and default to escaping for CMD
  // instead, resulting in the vulnerability.
  const options = {
    shell: "powershell",
    interpolation: true,
  };

  // 3. Using shescape to protect against attacks, this is correct.
  const escaped = shescape.escape("&& ls", options);

  // 4. Invoking a command with the escaped user input, this is vulnerable in
  // this case.
  exec(`echo Hello ${escaped}`, options, (error, stdout) => {
    if (error) {
      console.error(`An error occurred: ${error}`);
    } else {
      console.log(stdout);
    }
  });
}

Patches

This bug has been patched in v1.7.4 which you can upgrade to now. No further changes are required.

Workarounds

If you are impacted there is no workaround possible.

References

Shescape Pull Request #1142
Shescape commit 0b976da
Shescape release v1.7.4

For more information

Comment on Pull Request #1142
Comment on commit 0b976da
Open an issue at https://github.com/ericcornelissen/shescape/issues (New issue > Question > Get started)

1 year ago

ghsa

Open in Source

#vulnerability #windows #nodejs #js #git #java

Impact

This snippet demonstrates a vulnerable use of Shescape:

// vulnerable.js

import { exec } from "node:child_process"; import { Worker, isMainThread } from 'node:worker_threads’;

import * as shescape from "shescape";

if (isMainThread) { // 1. Something like a worker thread must be used. The reason being that they // unexpectedly change environment variable names on Windows. new Worker(“./vulnerable.js”); } else { // 2. Example configuration that’s problematic. In this setup example the // expected default system shell is CMD. We configure the use of PowerShell. // Shescape will fail to look up PowerShell and default to escaping for CMD // instead, resulting in the vulnerability. const options = { shell: "powershell", interpolation: true, };

// 3. Using shescape to protect against attacks, this is correct. const escaped = shescape.escape("&& ls", options);

// 4. Invoking a command with the escaped user input, this is vulnerable in // this case. exec(`echo Hello ${escaped}`, options, (error, stdout) => { if (error) { console.error(`An error occurred: ${error}`); } else { console.log(stdout); } }); }

Patches

This bug has been patched in v1.7.4 which you can upgrade to now. No further changes are required.

Workarounds

If you are impacted there is no workaround possible.

References

Shescape Pull Request #1142
Shescape commit 0b976da
Shescape release v1.7.4

For more information

Comment on Pull Request #1142
Comment on commit 0b976da
Open an issue at https://github.com/ericcornelissen/shescape/issues (New issue > Question > Get started)

References

GHSA-j55r-787p-m549
ericcornelissen/shescape#1142
ericcornelissen/shescape@0b976da
https://github.com/ericcornelissen/shescape/releases/tag/v1.7.4

shescape is simple shell escape library for JavaScript. This may impact users that use Shescape on Windows in a threaded context. The vulnerability can result in Shescape escaping (or quoting) for the wrong shell, thus allowing attackers to bypass protections depending on the combination of expected and used shell. This bug has been patched in version 1.7.4.

1 year ago

CVE

Open in Source

#vulnerability #windows #java