Ecosyste.ms: Advisories

Security Advisories: GSA_kwCzR0hTQS1qZzgyLXhoM3ctcmh4eM4AA2jA

Synchrony deobfuscator prototype pollution vulnerability leading to arbitrary code execution

Impact

A __proto__ pollution vulnerability exists in synchrony versions before v2.4.4. Successful exploitation could lead to arbitrary code execution.

Summary

A __proto__ pollution vulnerability exists in the LiteralMap transformer allowing crafted input to modify properties in the Object prototype.

When executing in Node.js, due to use of the prettier module, defining a parser property on __proto__ with a path to a JS module on disk causes a require of the value which can lead to arbitrary code execution.

Patch

A fix has been released in [email protected].

Mitigation

• Upgrade synchrony to v2.4.4
• Launch node with the --disable-proto=delete or --disable-proto=throw flag

Proof of Concept

Craft a malicious input file named poc.js as follows:

// Malicious code to be run after this file is imported. Logs the result of shell command "dir" to the console.
console.log(require('child_process').execSync('dir').toString())

// Synchrony exploit PoC
{
  var __proto__ = { parser: 'poc.js' }
}

Then, run synchrony poc.js from the same directory as the malicious file.

Credits

This vulnerability was found and disclosed by William Khem-Marquez.

Permalink: https://github.com/advisories/GHSA-jg82-xh3w-rhxx
JSON: https://advisories.ecosyste.ms/api/v1/advisories/GSA_kwCzR0hTQS1qZzgyLXhoM3ctcmh4eM4AA2jA
Source: GitHub Advisory Database
Origin: Unspecified
Severity: High
Classification: General
Published: about 1 year ago
Updated: about 1 year ago

CVSS Score: 7.8
CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Percentage: 0.00043
EPSS Percentile: 0.10511

Identifiers: GHSA-jg82-xh3w-rhxx, CVE-2023-45811
References:

• https://github.com/relative/synchrony/security/advisories/GHSA-jg82-xh3w-rhxx
• https://nvd.nist.gov/vuln/detail/CVE-2023-45811
• https://github.com/relative/synchrony/commit/b583126be94c4db7c5a478f1c5204bfb4162cf40
• https://github.com/relative/synchrony/security/advisories/src/transformers/literalmap.ts
• https://github.com/advisories/GHSA-jg82-xh3w-rhxx

Repository: https://github.com/relative/synchrony
Blast Radius: 8.4

Affected Packages