CVE-2023-20244
📋 TL;DR
An unauthenticated remote attacker can send crafted packets to Cisco Firepower Threat Defense (FTD) Software on Firepower 2100 Series Firewalls, causing a denial of service by depleting memory blocks. This results in traffic loss or device reload, affecting organizations using vulnerable FTD versions.
💻 Affected Systems
- Cisco Firepower Threat Defense (FTD) Software
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete traffic disruption requiring manual device reload, potentially causing extended network downtime.
Likely Case
Traffic loss across the firewall leading to service disruption until device recovers or is reloaded.
If Mitigated
Minimal impact if patched or workarounds implemented; isolated traffic issues if detected early.
🎯 Exploit Status
Exploitation requires sending specific packet sequences to trigger the memory depletion condition.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: FTD 7.2.5.1 and later, 7.4.1 and later
Vendor Advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-intrusion-dos-DfT7wyGC
Restart Required: Yes
Instructions:
1. Download appropriate FTD patch from Cisco. 2. Backup configuration. 3. Apply patch via FTD management interface. 4. Reboot device as required.
🔧 Temporary Workarounds
Access Control Restrictions
allLimit network access to FTD management and inspection interfaces to trusted sources only.
Configure ACLs to restrict traffic to FTD interfaces from authorized IP ranges only.
🧯 If You Can't Patch
- Implement strict network segmentation to limit exposure to untrusted networks.
- Monitor device memory usage and logs for signs of memory depletion or unusual packet patterns.
🔍 How to Verify
Check if Vulnerable:
Check FTD version via CLI: 'show version' and compare to affected versions (prior to 7.2.5.1 or 7.4.1).Check Version:
show version | include VersionVerify Fix Applied:
Confirm version is 7.2.5.1 or later, or 7.4.1 or later using 'show version' command.📡 Detection & Monitoring
Log Indicators:
- Memory allocation failures
- Unexpected device reloads
- High packet drop rates in inspection engine logs
Network Indicators:
- Sudden traffic loss through firewall
- Unusual packet patterns to FTD interfaces
- Device becoming unresponsive
SIEM Query:
Search for logs containing 'memory depletion', 'packet processing error', or 'unexpected reload' from FTD devices.