CVE-2023-31315
📋 TL;DR
This AMD processor vulnerability allows malicious software with kernel-level (ring0) access to bypass System Management Mode (SMM) protections and modify SMM configuration while SMI lock is enabled. This could lead to arbitrary code execution at the highest privilege level (ring-2). Affects systems with specific AMD processors when running untrusted code with kernel privileges.
💻 Affected Systems
- AMD Ryzen processors
- AMD EPYC processors
- AMD Threadripper processors
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with ring-2 privilege escalation, allowing attackers to bypass all security controls, install persistent firmware-level malware, and access all system memory and resources.
Likely Case
Privilege escalation from kernel to SMM level by malware already running with kernel access, enabling deeper persistence and evasion of security software.
If Mitigated
Limited impact if proper application whitelisting and kernel integrity protections prevent unauthorized kernel-level code execution.
🎯 Exploit Status
Exploit requires kernel-level access first; demonstrated at DEF CON 32 with proof-of-concept; not known to be in widespread attacks.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: AMD AGESA firmware updates - specific versions vary by motherboard manufacturer
Vendor Advisory: https://www.amd.com/en/resources/product-security/bulletin/amd-sb-7014.html
Restart Required: Yes
Instructions:
1. Check motherboard manufacturer website for BIOS/UEFI updates. 2. Download latest firmware with AGESA updates. 3. Follow manufacturer's firmware update procedure. 4. Reboot system.
🔧 Temporary Workarounds
Restrict kernel module loading
linuxPrevent unauthorized kernel modules from loading to reduce attack surface
echo 1 > /proc/sys/kernel/modules_disabled
sysctl -w kernel.modules_disabled=1
Enable Secure Boot
allEnsure only signed kernel and drivers can load
🧯 If You Can't Patch
- Implement strict application control/whitelisting to prevent unauthorized kernel-level code execution
- Use virtualization/isolation for high-risk workloads to contain potential privilege escalation
🔍 How to Verify
Check if Vulnerable:
Check BIOS/UEFI version against motherboard manufacturer's patched versions; no simple command-line check availableCheck Version:
On Linux: sudo dmidecode -t bios | grep Version; On Windows: wmic bios get smbiosbiosversionVerify Fix Applied:
Verify BIOS/UEFI version has been updated to patched version from manufacturer📡 Detection & Monitoring
Log Indicators:
- Unexpected kernel module loads
- BIOS/UEFI modification attempts
- SMI handler anomalies
Network Indicators:
- None - local exploitation only
SIEM Query:
DeviceLogs | where EventID == 6005 or EventID == 6006 | where DeviceVendor == "BIOS" | summarize count() by DeviceName🔗 References
- https://www.amd.com/en/resources/product-security/bulletin/amd-sb-7014.html
- https://media.defcon.org/DEF%20CON%2032/DEF%20CON%2032%20presentations/DEF%20CON%2032%20-%20Enrique%20Nissim%20Krzysztof%20Okupski%20-%20AMD%20Sinkclose%20Universal%20Ring-2%20Privilege%20Escalation.pdf
- https://news.ycombinator.com/item?id=41475975
- https://www.darkreading.com/remote-workforce/amd-issues-updates-for-silicon-level-sinkclose-flaw
