CVE-2020-24978
📋 TL;DR
CVE-2020-24978 is a double-free vulnerability in NASM (Netwide Assembler) that could allow attackers to execute arbitrary code or cause denial of service. This affects systems using NASM 2.15.04rc3 for assembly compilation, potentially impacting developers, build systems, and software distribution pipelines.
💻 Affected Systems
- NASM (Netwide Assembler)
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, or persistent backdoor installation.
Likely Case
Application crash or denial of service when processing malicious assembly files, disrupting build processes.
If Mitigated
Limited impact if NASM runs in sandboxed environments with minimal privileges and input validation.
🎯 Exploit Status
Exploitation requires feeding malicious assembly files to NASM. No public exploit code is documented, but the vulnerability type suggests reliable exploitation is possible.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in commit 8806c3ca007b84accac21dd88b900fb03614ceb7 and later versions
Vendor Advisory: https://bugzilla.nasm.us/show_bug.cgi?id=3392712
Restart Required: No
Instructions:
1. Update NASM to version 2.15.04 or later. 2. For source installations: git pull from NASM repository and rebuild. 3. For package managers: Use system package manager to update nasm package.
🔧 Temporary Workarounds
Input validation and sanitization
allValidate and sanitize assembly files before processing with NASM
Run NASM in restricted environment
linuxExecute NASM with minimal privileges using sandboxing or containerization
docker run --read-only --cap-drop=ALL -v $(pwd):/workdir nasm:latest
🧯 If You Can't Patch
- Restrict NASM usage to trusted users and processes only
- Monitor NASM processes for abnormal behavior and crashes
🔍 How to Verify
Check if Vulnerable:
Run 'nasm -v' and check if output shows version 2.15.04rc3Check Version:
nasm -vVerify Fix Applied:
Verify NASM version is 2.15.04 or later, or check git commit hash includes fix📡 Detection & Monitoring
Log Indicators:
- NASM process crashes with segmentation faults
- Unexpected NASM child process creation
Network Indicators:
- Unusual network connections from build systems
SIEM Query:
Process:name='nasm' AND (EventID=1000 OR EventID=1001) OR Process:parent_name='nasm'