CVE-2023-20107
📋 TL;DR
This vulnerability allows unauthenticated remote attackers to discover private cryptographic keys on affected Cisco ASA/FTD devices due to insufficient entropy in the random number generator. Attackers can impersonate devices or decrypt secured traffic. Affects Cisco ASA 5506-X, 5508-X, and 5516-X firewalls running vulnerable software.
💻 Affected Systems
- Cisco Adaptive Security Appliance (ASA) Software
- Cisco Firepower Threat Defense (FTD) Software
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of encrypted communications, device impersonation allowing network infiltration, and decryption of sensitive data in transit.
Likely Case
Targeted attacks against specific organizations to decrypt VPN traffic or impersonate firewall devices for lateral movement.
If Mitigated
Limited impact with proper network segmentation, monitoring, and quick patching, though cryptographic compromise remains serious.
🎯 Exploit Status
Exploitation requires generating large numbers of cryptographic keys and identifying collisions, making it computationally intensive but feasible for determined attackers.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Multiple fixed versions available - see Cisco advisory for specific fixed releases
Vendor Advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asa5500x-entropy-6v9bHVYP
Restart Required: Yes
Instructions:
1. Review Cisco advisory for specific fixed versions. 2. Download appropriate software from Cisco. 3. Backup configuration. 4. Apply update following Cisco ASA/FTD upgrade procedures. 5. Verify successful update and functionality.
🔧 Temporary Workarounds
No direct workaround available
allThis is a cryptographic vulnerability in hardware-specific entropy generation with no configuration-based workaround.
🧯 If You Can't Patch
- Replace affected hardware with non-vulnerable models if patching is not possible
- Implement additional network segmentation and monitoring for traffic to/from affected devices
🔍 How to Verify
Check if Vulnerable:
Check device model and software version against Cisco advisory. Use 'show version' command on ASA/FTD CLI.Check Version:
show versionVerify Fix Applied:
Verify software version is updated to fixed release listed in Cisco advisory using 'show version' command.📡 Detection & Monitoring
Log Indicators:
- Unusual cryptographic operations
- Multiple key generation attempts
- Failed authentication attempts from unexpected sources
Network Indicators:
- Unusual traffic patterns to/from firewall management interfaces
- Suspicious cryptographic handshake attempts
SIEM Query:
Search for multiple failed authentication attempts or unusual cryptographic operations on ASA/FTD devices