cve-2023-5678

# THREAT ADVISORY: CVE-2023-5678 OpenSSL X9.42 DH DoS Vulnerability **Advisory ID:** TA-2024-001 **Severity:** HIGH EXPOSURE (CVSS 5.3 - Medium) **Date:** Current **Classification:** Internal Use --- ## Executive Summary **IMMEDIATE ACTION REQUIRED** - Your organization has HIGH exposure to CVE-2023-5678, a denial-of-service vulnerability in OpenSSL's X9.42 Diffie-Hellman key handling. While this CVE has a medium CVSS score, your active use of DH key exchange combined with accepting untrusted DH parameters creates a direct attack path that could impact your mission-critical production services. **Key Concern:** Attackers can craft malicious DH keys/parameters to cause excessive processing delays, potentially triggering service outages across your web servers and applications. --- ## Your Exposure Status ✅ **CONFIRMED HIGH RISK FACTORS:** - Active DH key exchange implementation - Accepting DH keys/parameters from untrusted sources - Mission-critical production services at risk - Web servers/applications in scope ⚠️ **VERSION UNCERTAINTY:** - Running OpenSSL 1.0.x (likely not vulnerable to this specific CVE) - Unknown/Mixed versions present **critical blind spot** - Newer OpenSSL versions may be vulnerable 🛡️ **MITIGATING FACTORS:** - SSL/TLS implementation not affected - FIPS providers (if using OpenSSL 3.0/3.1) not affected --- ## What This Means For You **Immediate Risk:** An attacker can submit specially crafted DH parameters to your web applications, causing: - Excessive CPU consumption during key generation/validation - Service timeouts and potential outages - Cascading failures across mission-critical services **Business Impact:** Given your requirement for significant planning/downtime for patches, any successful DoS attack could have extended impact on operations. --- ## Recommended Actions ### 🚨 TODAY (Within 24 Hours) 1. **INVENTORY YOUR OPENSSL VERSIONS** ```bash # Run on all systems openssl version -a # Check linked libraries ldd /usr/bin/openssl | grep ssl ``` 2. **IDENTIFY VULNERABLE INSTANCES** - Focus on any OpenSSL 3.0.x or 3.1.x installations - Document which services use DH key exchange 3. **IMPLEMENT IMMEDIATE MONITORING** ```bash # Monitor for unusual CPU spikes in OpenSSL processes top -p $(pgrep -d',' -f openssl) # Watch for DH-related errors in logs grep -i "DH_generate_key\|DH_check_pub_key" /var/log/messages ``` ### 📋 THIS WEEK (Within 7 Days) 4. **VALIDATE DH PARAMETER SOURCES** - Review all applications accepting DH parameters from external sources - Implement parameter size limits if not already present - Consider pre-approved DH parameter sets 5. **TEST COMPENSATING CONTROLS** - Verify connection timeouts are properly configured - Test rate limiting on DH key exchange operations - Validate monitoring alerts for service degradation ### 🔧 PLANNED REMEDIATION (Within 30 Days) 6. **PATCH VULNERABLE SYSTEMS** - Prioritize any OpenSSL 3.0.x/3.1.x instances - Plan maintenance windows for mission-critical services - Test patches in staging environment first 7. **ARCHITECTURAL REVIEW** - Consider migrating to ECDH where possible - Evaluate necessity of accepting external DH parameters - Implement defense-in-depth measures --- ## Detection & Monitoring **Immediate Indicators:** - Unusual CPU spikes in OpenSSL processes - Application timeouts during key exchange - Memory exhaustion on crypto-intensive services **Log Monitoring:** ```bash # Monitor for DH-related delays grep -E "(DH_generate_key|DH_check_pub_key|timeout)" /var/log/application.log # Watch for service degradation journalctl -u your-web-service -f | grep -i "slow\|timeout\|delay" ``` **Performance Baselines:** - Establish normal DH operation timing - Set alerts for >5x normal processing time - Monitor connection queue depths --- ## References - **CVE Details:** [CVE-2023-5678](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-5678) - **OpenSSL Security Advisory:** [OpenSSL Advisory](https://www.openssl.org/news/secadv/) - **Patch Information:** Check OpenSSL release notes for your version - **NIST NVD:** [NVD Entry](https://nvd.nist.gov/vuln/detail/CVE-2023-5678) --- **Next Review:** 7 days **Prepared by:** CISO Office **Distribution:** Infrastructure Team, Application Security, Operations *This advisory is based on your organization's specific exposure assessment. Contact the security team for clarification on any recommendations.*