CVE-2020-24489
📋 TL;DR
This vulnerability in Intel VT-d (Virtualization Technology for Directed I/O) allows an authenticated attacker with local access to potentially escalate privileges due to incomplete cleanup in DMA (Direct Memory Access) remapping. It affects systems with Intel processors that have VT-d enabled. The attacker could gain higher privileges on the system.
💻 Affected Systems
- Intel processors with VT-d technology
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
An authenticated attacker gains kernel-level privileges, potentially taking full control of the system, accessing sensitive data, or installing persistent malware.
Likely Case
An authenticated user with local access escalates to root/admin privileges, compromising the system's integrity and confidentiality.
If Mitigated
With proper access controls and patching, the risk is reduced to minimal, though the vulnerability remains present but unexploitable.
🎯 Exploit Status
Exploitation requires local access and authentication, making it less likely for widespread attacks but serious in multi-user or shared environments.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Microcode updates and OS patches as per vendor advisories (e.g., Debian security updates)
Vendor Advisory: https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00442.html
Restart Required: Yes
Instructions:
1. Check Intel advisory for specific processor updates. 2. Apply microcode updates via BIOS/UEFI or OS. 3. Apply OS patches (e.g., for Debian: apt update && apt upgrade). 4. Reboot the system.
🔧 Temporary Workarounds
Disable VT-d in BIOS/UEFI
allTurn off Intel VT-d feature to mitigate the vulnerability, but this may impact virtualization performance.
Restrict local access
allLimit user accounts with local access to trusted individuals only.
🧯 If You Can't Patch
- Isolate affected systems from critical networks and data.
- Implement strict access controls and monitor for suspicious local activity.
🔍 How to Verify
Check if Vulnerable:
Check if VT-d is enabled: on Linux, run 'dmesg | grep -i vt-d' or 'cat /proc/cpuinfo | grep vt-d'. If enabled and unpatched, assume vulnerable.Check Version:
On Linux: 'uname -a' for kernel, 'cat /etc/os-release' for OS version.Verify Fix Applied:
Verify microcode version: on Linux, run 'cat /proc/cpuinfo | grep microcode'. Check OS patch status: on Debian, run 'apt list --installed | grep intel-microcode' or related packages.📡 Detection & Monitoring
Log Indicators:
- Unusual privilege escalation attempts in system logs (e.g., /var/log/auth.log)
- Kernel panic or crashes related to DMA operations
Network Indicators:
- Not typically network-exploitable; focus on local system monitoring
SIEM Query:
Example: search for 'sudo' or 'su' failures followed by successes from same user in short time, or kernel logs with 'VT-d' errors.🔗 References
- https://lists.debian.org/debian-lts-announce/2021/07/msg00022.html
- https://www.debian.org/security/2021/dsa-4934
- https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00442.html
- https://lists.debian.org/debian-lts-announce/2021/07/msg00022.html
- https://www.debian.org/security/2021/dsa-4934
- https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00442.html
