CVE-2023-52892
📋 TL;DR
This vulnerability in phpseclib allows attackers to craft TLS certificates with special regex characters in Subject Alternative Name fields, potentially bypassing hostname verification. This could enable man-in-the-middle attacks or impersonation of trusted services. All applications using vulnerable phpseclib versions for TLS certificate validation are affected.
💻 Affected Systems
- phpseclib
📦 What is this software?
Phpseclib by Phpseclib
Phpseclib by Phpseclib
Phpseclib by Phpseclib
⚠️ Risk & Real-World Impact
Worst Case
Attackers could impersonate legitimate servers, intercept encrypted communications, steal sensitive data, or inject malicious content into trusted connections.
Likely Case
Targeted attacks against specific applications using phpseclib for TLS validation, potentially leading to credential theft or data interception.
If Mitigated
Limited impact if proper network segmentation, certificate pinning, or additional validation layers are in place.
🎯 Exploit Status
Proof-of-concept available in GitHub references. Exploitation requires ability to present malicious certificates to vulnerable applications.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: phpseclib 1.0.22, 2.0.46, 3.0.33 or later
Vendor Advisory: https://github.com/phpseclib/phpseclib/releases/tag/3.0.33
Restart Required: No
Instructions:
1. Update phpseclib via composer: 'composer update phpseclib/phpseclib' 2. Verify version meets minimum: 1.0.22+, 2.0.46+, or 3.0.33+ 3. Test TLS certificate validation functionality
🔧 Temporary Workarounds
Certificate Pinning
allImplement certificate pinning to validate specific certificates rather than relying solely on hostname verification
🧯 If You Can't Patch
- Implement network-level controls to restrict TLS connections to trusted endpoints only
- Deploy additional certificate validation layers or use alternative TLS libraries temporarily
🔍 How to Verify
Check if Vulnerable:
Check composer.json or installed packages for phpseclib version. Vulnerable if version <1.0.22, <2.0.46, or <3.0.33Check Version:
composer show phpseclib/phpseclib | grep versionVerify Fix Applied:
After update, verify phpseclib version meets minimum requirements and test with known malicious certificates from testing artifacts📡 Detection & Monitoring
Log Indicators:
- Unexpected certificate validation failures
- Connections to unusual hostnames with special characters
Network Indicators:
- TLS connections with certificates containing regex special characters in SAN fields
SIEM Query:
source="*tls*" AND ("certificate validation" OR "hostname mismatch") AND ("+" OR "*" OR "." OR "?" OR "[" OR "]")🔗 References
- https://github.com/phpseclib/phpseclib/commit/6cd6e8ceab9f2b55c8cd81d2192bf98cbeaf4627
- https://github.com/phpseclib/phpseclib/issues/1943
- https://github.com/phpseclib/phpseclib/releases/tag/3.0.33
- https://github.com/x509-name-testing/name_testing_artifacts
- https://github.com/phpseclib/phpseclib/commit/6cd6e8ceab9f2b55c8cd81d2192bf98cbeaf4627
- https://github.com/phpseclib/phpseclib/issues/1943
- https://github.com/phpseclib/phpseclib/releases/tag/3.0.33
- https://github.com/x509-name-testing/name_testing_artifacts
