Network intrusion-detection bypass via TCP timestamp mismatch
Published Jan 6, 2020 · Updated Aug 5, 2024
TCP stream evasion in OISF Suricata 4.1.5 and 5.0.0 allows remote attackers controlling a server to bypass TCP signatures. The SYN_SENT handler accepts forged RST/ACK and FIN/ACK packets with invalid TCP timestamp echoes, marks the tracked session closed, and skips later payload inspection. The target must inspect traffic between a Linux or Windows client and an attacker-controlled server; the client rejects the forged packets while Suricata accepts them.
Summary
What happened
TCP stream evasion in OISF Suricata 4.1.5 and 5.0.0 allows remote attackers controlling a server to bypass TCP signatures. The SYN_SENT handler accepts forged RST/ACK and FIN/ACK packets with invalid TCP timestamp echoes, marks the tracked session closed, and skips later payload inspection. The target must inspect traffic between a Linux or Windows client and an attacker-controlled server; the client rejects the forged packets while Suricata accepts them.
The record
- CVE
- CVE-2019-18625
- Published
- Jan 6, 2020
- Updated
- Aug 5, 2024
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- T1687
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jan 6, 2020CVE publishedPublication date reported by the CVE source.
- Aug 5, 2024Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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What conditions does exploitation require?
What is affected?
Affected products and versions are unavailable in this record.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- with_evasion_windows.pcapproof of concept · demonstrated
- with_evasion_linux.pcapproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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