CVE-2021-46756
📋 TL;DR
This vulnerability in AMD Secure Processor bootloader allows attackers with malicious user applications or ABL to send malformed syscalls, potentially causing denial of service and integrity loss. It affects systems with AMD processors containing the vulnerable ASP firmware.
💻 Affected Systems
- AMD processors with ASP (AMD Secure Processor)
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise including bootloader corruption, persistent denial of service, and potential privilege escalation to secure processor level.
Likely Case
System crashes, boot failures, and integrity violations requiring hardware-level recovery procedures.
If Mitigated
Limited impact with proper firmware updates and secure boot configurations preventing unauthorized code execution.
🎯 Exploit Status
Requires ability to execute malicious Uapp or ABL code, suggesting need for initial compromise or insider access.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check AMD firmware updates for specific product lines
Vendor Advisory: https://www.amd.com/en/corporate/product-security/bulletin/AMD-SB-3001
Restart Required: Yes
Instructions:
1. Identify AMD processor model and current firmware version
2. Visit AMD security bulletin page for applicable firmware updates
3. Follow manufacturer instructions for firmware flashing
4. Verify successful update and secure boot configuration
🔧 Temporary Workarounds
Secure Boot Enforcement
allEnable and enforce secure boot to prevent unauthorized Uapp/ABL execution
Check BIOS/UEFI settings for secure boot options
🧯 If You Can't Patch
- Implement strict application whitelisting to prevent unauthorized Uapp execution
- Isolate systems with vulnerable firmware from untrusted networks and users
🔍 How to Verify
Check if Vulnerable:
Check system firmware version against AMD security bulletins for affected versionsCheck Version:
Windows: wmic bios get smbiosbiosversion | Linux: sudo dmidecode -t biosVerify Fix Applied:
Verify firmware version has been updated to patched version listed in AMD advisories📡 Detection & Monitoring
Log Indicators:
- Unexpected system reboots
- Bootloader error messages
- Secure processor failure logs
Network Indicators:
- None - local exploitation only
SIEM Query:
EventID 6008 (Unexpected shutdown) OR boot-related errors in system logs