CVE-2021-21772
📋 TL;DR
This CVE describes a use-after-free vulnerability in lib3mf's ZIP file handling that allows remote code execution. Attackers can exploit it by tricking users into opening malicious 3MF files, potentially gaining control of affected systems. Any application using vulnerable versions of lib3mf is at risk.
💻 Affected Systems
- lib3mf
- Applications using lib3mf library
📦 What is this software?
Fedora by Fedoraproject
Fedora by Fedoraproject
Fedora by Fedoraproject
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining full control over the affected system, potentially leading to data theft, ransomware deployment, or lateral movement within the network.
Likely Case
Local privilege escalation or remote code execution when users open malicious 3MF files, leading to malware installation or data exfiltration.
If Mitigated
Denial of service or application crash if exploit fails, with no further system impact.
🎯 Exploit Status
Exploitation requires user interaction to open a malicious file, but the vulnerability itself is straightforward to trigger once the file is processed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: lib3mf 2.1.0 and later
Vendor Advisory: https://github.com/3MFConsortium/lib3mf/security/advisories
Restart Required: Yes
Instructions:
1. Update lib3mf to version 2.1.0 or later. 2. Rebuild any applications using lib3mf with the updated library. 3. Restart affected applications or services.
🔧 Temporary Workarounds
Disable 3MF file processing
allTemporarily disable or block processing of 3MF files in affected applications until patching is complete.
File type blocking
allUse application whitelisting or file type blocking to prevent execution of 3MF files.
🧯 If You Can't Patch
- Implement strict file upload controls and scanning for 3MF files
- Use application sandboxing or containerization to limit potential damage
🔍 How to Verify
Check if Vulnerable:
Check if applications use lib3mf version 2.0.0 by examining linked libraries or package versions.Check Version:
ldd /path/to/application | grep lib3mf (Linux) or check application dependenciesVerify Fix Applied:
Verify lib3mf version is 2.1.0 or later using package manager or library version checks.📡 Detection & Monitoring
Log Indicators:
- Application crashes when processing 3MF files
- Unexpected process execution following 3MF file handling
Network Indicators:
- Unexpected outbound connections after 3MF file processing
SIEM Query:
Process: (lib3mf OR *3mf*) AND (Crash OR Unexpected_execution)🔗 References
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IHMMHD2EOMIVJ7EKZTJJMX4C7E6ZRWDL/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NPBS642OYVA6DUKK3HZHEINVWEDZSMEU/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WDGGB65YBQL662M3MOBNNJJNRNURW4TG/
- https://security.gentoo.org/glsa/202208-01
- https://talosintelligence.com/vulnerability_reports/TALOS-2020-1226
- https://www.debian.org/security/2021/dsa-4887
- https://www.talosintelligence.com/vulnerability_reports/TALOS-2021-1226
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IHMMHD2EOMIVJ7EKZTJJMX4C7E6ZRWDL/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NPBS642OYVA6DUKK3HZHEINVWEDZSMEU/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WDGGB65YBQL662M3MOBNNJJNRNURW4TG/
- https://security.gentoo.org/glsa/202208-01
- https://talosintelligence.com/vulnerability_reports/TALOS-2020-1226
- https://www.debian.org/security/2021/dsa-4887
- https://www.talosintelligence.com/vulnerability_reports/TALOS-2021-1226
