CVE-2024-20261
📋 TL;DR
A vulnerability in Cisco Firepower Threat Defense (FTD) software allows attackers to bypass file policies that should block encrypted archive files. Unauthenticated remote attackers can send crafted encrypted archives containing malware through affected devices. Organizations using Cisco FTD with file policy inspection for encrypted archives are affected.
💻 Affected Systems
- Cisco Firepower Threat Defense (FTD)
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Malware-laden encrypted archives bypass security controls, leading to network compromise, data exfiltration, or ransomware deployment.
Likely Case
Attackers deliver malware payloads that would normally be blocked, potentially leading to endpoint infections within the protected network.
If Mitigated
With proper network segmentation and endpoint protection, malware delivery is detected and contained before causing significant damage.
🎯 Exploit Status
Exploitation requires sending crafted encrypted archives through the device
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 7.4.1 and later
Vendor Advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-archive-bypass-z4wQjwcN
Restart Required: Yes
Instructions:
1. Backup configuration 2. Download FTD 7.4.1+ from Cisco Software Center 3. Deploy update via FMC or CLI 4. Verify successful upgrade
🔧 Temporary Workarounds
Disable encrypted archive inspection
allTemporarily disable file policy inspection for encrypted archives to prevent bypass
Configure via FMC: Policies > Access Control > Edit policy > File Policy > Disable 'Inspect encrypted archives'
🧯 If You Can't Patch
- Implement network segmentation to limit potential malware spread
- Deploy additional endpoint detection and response (EDR) solutions
🔍 How to Verify
Check if Vulnerable:
Check FTD version via CLI: 'show version' and verify if below 7.4.1Check Version:
show version | include VersionVerify Fix Applied:
Verify version is 7.4.1+ and test file policy with encrypted archives📡 Detection & Monitoring
Log Indicators:
- Unexpected archive file transfers bypassing file policies
- Increased encrypted archive traffic
Network Indicators:
- Encrypted archive files from untrusted sources
- Archive files with unusual characteristics
SIEM Query:
source="ftd" AND (archive OR encrypted) AND action="allow" AND policy="file_policy"