CVE-2020-12951
📋 TL;DR
A race condition vulnerability in AMD's ASP firmware allows less privileged x86 code to perform System Management Mode operations. This affects AMD processors with vulnerable firmware versions, potentially enabling privilege escalation from user space to SMM.
💻 Affected Systems
- AMD Ryzen, EPYC, Athlon, and Ryzen PRO processors with AMD Secure Processor (ASP)
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise via SMM code execution, allowing attackers to bypass all security controls, install persistent firmware-level malware, and access protected memory regions.
Likely Case
Privilege escalation from user space to kernel or hypervisor level, enabling data theft, persistence mechanisms, or lateral movement within the environment.
If Mitigated
Limited impact if systems are fully patched and have additional security controls like secure boot enabled and SMM protections configured.
🎯 Exploit Status
Exploitation requires local code execution and precise timing due to race condition nature; no public exploits have been documented.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: AMD PSP firmware updates as specified in AMD-SB-1027 advisory
Vendor Advisory: https://www.amd.com/en/corporate/product-security/bulletin/amd-sb-1027
Restart Required: Yes
Instructions:
1. Check system manufacturer for BIOS/UEFI updates. 2. Apply firmware updates from system vendor. 3. Reboot system to activate new firmware. 4. Verify firmware version matches patched release.
🔧 Temporary Workarounds
Restrict local code execution
allLimit user privileges and application execution to reduce attack surface for local exploitation
Enable secure boot
allEnsure secure boot is enabled to prevent unauthorized firmware/OS modifications
🧯 If You Can't Patch
- Segment affected systems in isolated network zones to limit lateral movement potential
- Implement strict application whitelisting and least privilege access controls
🔍 How to Verify
Check if Vulnerable:
Check BIOS/UEFI firmware version against AMD advisory; use manufacturer-specific tools to query PSP firmware versionCheck Version:
Manufacturer-specific commands vary; on Linux: 'sudo dmidecode -t bios' or 'sudo cat /sys/class/dmi/id/bios_version'Verify Fix Applied:
Verify BIOS/UEFI firmware version matches patched release from system manufacturer; confirm no CVE-2020-12951 references in vulnerability scans📡 Detection & Monitoring
Log Indicators:
- Unexpected system reboots
- BIOS/UEFI modification attempts in system logs
- Privilege escalation alerts
Network Indicators:
- Unusual outbound connections from affected systems post-exploitation
SIEM Query:
EventID=6008 OR EventID=1074 OR (privilege_escalation AND source_process="*")