CVE-2023-46233: Crypto-js PBKDF2 Weak Hashing Vulnerability

CVE-2023-46233 Overview

CVE-2023-46233 is a critical weak cryptographic implementation vulnerability in crypto-js, a widely-used JavaScript library of crypto standards. Prior to version 4.2.0, the crypto-js PBKDF2 (Password-Based Key Derivation Function 2) implementation is dramatically weaker than originally specified—approximately 1,000 times weaker than the 1993 specification and at least 1,300,000 times weaker than current industry standards.

The vulnerability stems from two critical default configuration issues: the library defaults to SHA1 (a hash algorithm considered insecure since at least 2005) and defaults to a single iteration instead of the 1,000 iterations specified in the original 1993 PBKDF2 standard. PBKDF2 relies on iteration count as a countermeasure to preimage and collision attacks, making this misconfiguration particularly dangerous.

Critical Impact

Applications using crypto-js PBKDF2 with default settings for password protection or signature generation are vulnerable to significantly weakened cryptographic security, potentially enabling password cracking and signature forgery attacks.

Affected Products

• crypto-js versions prior to 4.2.0
• Applications using crypto-js PBKDF2 with default configuration
• Debian packages incorporating vulnerable crypto-js versions

Discovery Timeline

• 2023-10-25 - CVE-2023-46233 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-46233

Vulnerability Analysis

This vulnerability is classified under CWE-328 (Reversible One-Way Hash) and CWE-327 (Use of a Broken or Risky Cryptographic Algorithm). The core issue lies in the PBKDF2 implementation's default parameters, which fail to provide adequate cryptographic strength for modern security requirements.

PBKDF2 was designed to make password hashing computationally expensive, thereby slowing down brute-force and dictionary attacks. The iteration count is the primary mechanism for achieving this computational cost. By defaulting to a single iteration, crypto-js essentially negates the protective purpose of PBKDF2, reducing it to a simple hash function that can be attacked at near-native speed.

The use of SHA1 as the default hash algorithm compounds this problem. SHA1 has been deprecated for security-sensitive applications since 2005, and practical collision attacks have been demonstrated. For password hashing, this means reduced resistance to precomputed rainbow table attacks.

Root Cause

The root cause is an insecure default configuration in the PBKDF2 module. The library was configured to use SHA1 as the default hasher and only one iteration by default, rather than adhering to the original PBKDF2 specification of 1,000 iterations (which itself is now considered insufficient by modern standards—current recommendations suggest 250,000 or more iterations).

Attack Vector

This vulnerability can be exploited over the network without authentication. An attacker who obtains password hashes or derived keys generated using the vulnerable PBKDF2 implementation can:

1. Perform rapid brute-force attacks due to the single iteration default
2. Leverage existing SHA1 rainbow tables and precomputed hash databases
3. Crack passwords at speeds 1,300,000 times faster than industry-standard implementations
4. Forge signatures if PBKDF2 is used in signature generation workflows

The following code shows the security patch that changes the default hash algorithm from SHA1 to SHA256:

     var Base = C_lib.Base;
     var WordArray = C_lib.WordArray;
     var C_algo = C.algo;
-    var SHA1 = C_algo.SHA1;
+    var SHA256 = C_algo.SHA256;
     var HMAC = C_algo.HMAC;

Source: GitHub Commit Update

The module configuration was also updated to include SHA256 as a dependency instead of SHA1:

             },
             "pbkdf2": {
                 "exports": "CryptoJS.PBKDF2",
-                "components": ["core", "sha1", "hmac", "pbkdf2"]
+                "components": ["core", "sha256", "hmac", "pbkdf2"]
             },
             "evpkdf": {
                 "exports": "CryptoJS.EvpKDF",

Source: GitHub Commit Update

Detection Methods for CVE-2023-46233

Indicators of Compromise

• Applications using crypto-js versions prior to 4.2.0 in their dependency tree
• Code patterns calling CryptoJS.PBKDF2() without explicitly specifying hasher and iterations parameters
• Package manifests (package.json, package-lock.json) referencing vulnerable crypto-js versions
• Weak password hashes that can be cracked unusually quickly during security assessments

Detection Strategies

• Conduct Software Composition Analysis (SCA) scans to identify crypto-js versions below 4.2.0
• Perform code reviews searching for PBKDF2 function calls without explicit secure configuration
• Implement dependency vulnerability scanning in CI/CD pipelines using tools like npm audit, Snyk, or OWASP Dependency-Check
• Review application logs and authentication systems for signs of brute-force attacks that may indicate weak password hashing

Monitoring Recommendations

• Monitor npm audit reports for crypto-js vulnerabilities during development and deployment
• Track authentication failure patterns that could indicate exploitation of weak password hashes
• Implement alerts for high-volume password verification attempts against user accounts
• Review software bill of materials (SBOM) for presence of vulnerable crypto-js versions across your application portfolio

How to Mitigate CVE-2023-46233

Immediate Actions Required

• Upgrade crypto-js to version 4.2.0 or later immediately
• Audit all existing code for PBKDF2 usage and ensure secure parameters are explicitly configured
• Consider re-hashing stored passwords with secure parameters upon user's next successful login
• Conduct a security assessment to determine if password databases may have been compromised

Patch Information

The crypto-js maintainers have released version 4.2.0 which addresses this vulnerability by changing the default hash algorithm to SHA256. The patch is available in the GitHub Commit Update. Additional details are available in the GitHub Security Advisory.

Debian users should refer to the Debian LTS Announcement for distribution-specific patches.

Workarounds

• Explicitly configure PBKDF2 to use SHA256 or SHA512 as the hasher algorithm
• Set iteration count to at least 250,000 (current industry recommendation)
• If upgrading is not immediately possible, wrap all PBKDF2 calls with secure default parameters
• Consider migrating to more modern key derivation functions like Argon2 or scrypt for new implementations

# Configuration example
# Update crypto-js to patched version
npm update crypto-js@^4.2.0

# Verify installation
npm list crypto-js

# Run security audit to confirm resolution
npm audit