CVE-2024-55629
📋 TL;DR
This vulnerability in Suricata allows attackers to evade detection by using TCP urgent data (out-of-band data) to make Suricata analyze network traffic differently than the actual endpoints. This affects all Suricata users running versions before 7.0.8 in IDS/IPS/NSM modes. The evasion could allow malicious traffic to bypass security monitoring.
💻 Affected Systems
- Suricata
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers completely bypass Suricata's detection capabilities, allowing malware delivery, data exfiltration, or command-and-control traffic to go undetected.
Likely Case
Targeted evasion attacks against specific Suricata rules, allowing certain malicious activities to bypass detection while other traffic is still monitored.
If Mitigated
Minimal impact with proper configuration or patching, as Suricata can be configured to handle TCP urgent data appropriately.
🎯 Exploit Status
Exploitation requires crafting TCP packets with urgent flag manipulation. No public exploit code is known, but the technique is documented in the advisory.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 7.0.8
Vendor Advisory: https://github.com/OISF/suricata/security/advisories/GHSA-69wr-vhwg-84h2
Restart Required: No
Instructions:
1. Upgrade Suricata to version 7.0.8 or later. 2. Update configuration to set 'tcp.urgent-data' to 'ignore' or 'process' based on your needs. 3. Reload Suricata configuration without restart using 'suricatasc -c reload-rules' or similar.
🔧 Temporary Workarounds
Drop TCP urgent packets in IPS mode
allConfigure Suricata in IPS mode to drop all packets with TCP urgent flag set
drop tcp any any -> any any (sid:1; tcp.flags:U*;)
🧯 If You Can't Patch
- Configure Suricata to ignore TCP urgent data by setting 'tcp.urgent-data: ignore' in suricata.yaml
- Implement network-level filtering to drop TCP packets with urgent flag at firewall or router level
🔍 How to Verify
Check if Vulnerable:
Check Suricata version with 'suricata --build-info' or 'suricata -V'. If version is below 7.0.8, you are vulnerable.Check Version:
suricata --build-info | grep VersionVerify Fix Applied:
Verify version is 7.0.8 or higher and check configuration includes 'tcp.urgent-data' setting. Test with crafted TCP urgent packets to ensure proper handling.📡 Detection & Monitoring
Log Indicators:
- Unusual TCP flag combinations in Suricata logs
- TCP packets with urgent flag set in network traffic logs
Network Indicators:
- TCP packets with URG flag set in suspicious contexts
- Multiple TCP sessions with urgent data manipulation
SIEM Query:
source="suricata" AND (tcp.flags="URG" OR tcp.flags="URG,ACK") AND NOT (dest_port IN (20,21,22,23,25,53,80,110,143,443,993,995))