CVE-2018-14568 in Suricata
Summary
by MITRE
Suricata before 4.0.5 stops TCP stream inspection upon a TCP RST from a server. This allows detection bypass because Windows TCP clients proceed with normal processing of TCP data that arrives shortly after an RST (i.e., they act as if the RST had not yet been received).
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Analysis
by VulDB Data Team • 04/25/2023
The vulnerability identified as CVE-2018-14568 represents a critical flaw in the Suricata network intrusion detection system that affects versions prior to 4.0.5. This issue stems from the system's handling of TCP reset packets and creates a significant detection bypass opportunity that adversaries can exploit to evade security monitoring. The flaw specifically impacts how Suricata processes TCP stream inspection when encountering TCP RST (reset) packets originating from server endpoints, fundamentally altering the expected behavior of network traffic analysis.
The technical root cause of this vulnerability lies in Suricata's stream reassembly logic which terminates TCP stream inspection upon receiving a TCP RST packet from a server. This behavior deviates from standard TCP protocol handling where client systems typically continue processing data that arrives shortly after receiving a reset packet. Microsoft Windows TCP clients, which represent a significant portion of network traffic, implement this graceful degradation behavior by continuing to process incoming data even after receiving an RST, effectively ignoring the reset signal for a brief period. This Windows-specific behavior creates a window of opportunity where malicious traffic can bypass detection mechanisms that rely on proper TCP stream termination.
The operational impact of this vulnerability extends beyond simple detection bypass to encompass broader network security implications. When Suricata stops inspecting TCP streams upon receiving a server RST, it fails to analyze potentially malicious data that continues flowing through the network connection despite the reset signal. This creates a false sense of security where network administrators believe traffic has been properly terminated, while in reality, the system has failed to perform critical inspection of data that may contain exploits, malware payloads, or other malicious content. The vulnerability particularly affects environments where Suricata is used for deep packet inspection and protocol analysis, potentially allowing attackers to deliver payloads that would otherwise be detected by signature-based or anomaly-based detection rules.
This vulnerability maps to CWE-1190 which describes improper handling of TCP reset packets in network protocol stacks, and aligns with ATT&CK technique T1071.004 for application layer protocol communication. The flaw demonstrates a fundamental mismatch between the detection system's behavior and the actual TCP protocol implementation in client systems, creating a gap that adversaries can leverage for persistent attacks. Organizations using Suricata for network monitoring and intrusion detection face significant risk as this vulnerability can allow attackers to bypass security controls that depend on proper TCP stream termination and inspection. The impact is particularly severe in environments where TCP-based attacks are common, such as web application attacks, data exfiltration attempts, or command and control communications that rely on maintaining persistent connections.
Mitigation strategies for CVE-2018-14568 primarily focus on upgrading to Suricata version 4.0.5 or later, which includes corrected stream handling logic for TCP RST packets. Network administrators should also implement additional monitoring and logging to detect unusual TCP behavior patterns that may indicate exploitation attempts. Organizations should consider implementing complementary security controls such as network segmentation, application firewalls, and endpoint detection systems to provide defense in depth. Regular security assessments of network monitoring systems should include verification of proper TCP stream handling behavior, particularly in environments where Windows clients are prevalent and where the specific interaction between network detection systems and client TCP implementations may create exploitable gaps in security coverage.