CVE-2011-4574
📋 TL;DR
CVE-2011-4574 is a critical vulnerability in PolarSSL's HAVEGE random number generator that produces weak cryptographic keys when virtualized environments disable the RDTSC instruction. This allows attackers to predict or brute-force encryption keys, compromising TLS/SSL security. Systems using PolarSSL v1.0 and earlier in virtualized environments are primarily affected.
💻 Affected Systems
- PolarSSL (now mbed TLS)
- Any software embedding PolarSSL library
📦 What is this software?
Polarssl by Polarssl
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of encrypted communications allowing decryption of TLS/SSL traffic, session hijacking, and man-in-the-middle attacks against affected systems.
Likely Case
Weakened cryptographic protection making encrypted communications vulnerable to brute-force attacks and cryptographic analysis.
If Mitigated
Limited impact with proper network segmentation, monitoring, and updated software versions.
🎯 Exploit Status
Exploitation requires access to encrypted communications and knowledge of the weak random number generation pattern.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: PolarSSL v1.1 and later
Vendor Advisory: https://tls.mbed.org/tech-updates/security-advisories/polarssl-security-advisory-2011-02
Restart Required: Yes
Instructions:
1. Upgrade PolarSSL to version 1.1 or later. 2. Recompile any applications using PolarSSL. 3. Restart affected services. 4. Regenerate cryptographic keys and certificates.
🔧 Temporary Workarounds
Disable HAVEGE in configuration
allConfigure PolarSSL to use alternative random number generators instead of HAVEGE
Set POLARSSL_HAVEGE_C to 0 in config.h and recompile
Enable RDTSC in hypervisor
allConfigure virtualization platform to allow RDTSC instruction passthrough
🧯 If You Can't Patch
- Isolate affected systems in separate network segments with strict access controls
- Implement additional encryption layer (VPN/IPsec) for critical communications
🔍 How to Verify
Check if Vulnerable:
Check PolarSSL version and verify if compiled with HAVEGE support in virtualized environmentCheck Version:
Check application documentation or use strings command on binary: strings binary | grep -i polarsslVerify Fix Applied:
Verify PolarSSL version is 1.1+ and test random number generation quality📡 Detection & Monitoring
Log Indicators:
- Failed cryptographic operations
- Unexpected connection resets during TLS handshake
Network Indicators:
- Unusual patterns in encrypted traffic
- Multiple failed TLS handshakes
SIEM Query:
Search for PolarSSL version strings in application logs and system inventory