CVE-2018-9258 in Wireshark
Summary
by MITRE
In Wireshark 2.4.0 to 2.4.5, the TCP dissector could crash. This was addressed in epan/dissectors/packet-tcp.c by preserving valid data sources.
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Analysis
by VulDB Data Team • 02/26/2023
The vulnerability identified as CVE-2018-9258 represents a critical denial of service flaw within Wireshark's TCP dissector component. This issue affected versions 2.4.0 through 2.4.5 of the popular network protocol analyzer, where specific malformed TCP packets could trigger a crash in the application's packet dissection engine. The vulnerability stems from improper handling of data sources during TCP packet processing, creating a condition where the dissector would fail when encountering certain packet structures that contained invalid or unexpected data references. The flaw specifically manifested in the epan/dissectors/packet-tcp.c file, which serves as the core implementation for TCP protocol analysis within Wireshark's dissectors framework.
The technical nature of this vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and more specifically relates to improper handling of data sources in protocol dissectors. When Wireshark's TCP dissector encountered malformed packets with invalid data pointers or corrupted packet structures, the application would attempt to access memory locations that either did not exist or contained invalid data. This improper memory access pattern caused the application to terminate unexpectedly, resulting in a complete crash of the packet analysis session. The vulnerability was particularly concerning because it could be triggered by simply capturing and analyzing a single malformed TCP packet, making it exploitable by anyone who could influence network traffic or had access to packet capture files containing such malicious data.
The operational impact of CVE-2018-9258 extends beyond simple application instability, as it represents a significant threat to network analysis workflows and security operations. Network security professionals who rely on Wireshark for traffic analysis, incident response, and protocol debugging could find their analysis sessions abruptly terminated when encountering malicious or malformed packets in their captures. This vulnerability effectively created a denial of service condition that could prevent security teams from performing critical network forensic analysis, potentially masking malicious activities or preventing the identification of security incidents. The crash would occur during the packet dissection phase, meaning that even if the packet capture file itself was valid, the presence of a single malformed TCP packet could cause the entire analysis session to fail, forcing analysts to restart their investigations and potentially lose valuable context.
The mitigation for this vulnerability was implemented through careful data source validation within the TCP dissector code. The fix in epan/dissectors/packet-tcp.c specifically addressed the preservation of valid data sources by ensuring that the dissector would properly validate memory references before attempting to access them. This approach aligns with ATT&CK technique T1489, which involves denying access to resources by causing system crashes or disabling services. By implementing proper bounds checking and data validation, the Wireshark development team ensured that the dissector would gracefully handle malformed input rather than crashing. Users were advised to upgrade to Wireshark version 2.4.6 or later, which contained the patched dissector implementation. Organizations relying on Wireshark for network monitoring, security analysis, and forensic investigations should have prioritized this update to maintain system stability and prevent potential service disruptions during critical analysis tasks.
The vulnerability serves as a reminder of the importance of robust input validation in network protocol analysis tools, where the handling of malformed data can have cascading effects on application stability. This flaw demonstrates how protocol dissectors must account for the possibility of encountering corrupted or malicious network data, as these tools often process untrusted input from network traffic. The fix implemented represents a standard defensive programming approach that emphasizes proper resource management and error handling in network analysis applications, ensuring that the tools remain stable even when processing unexpected or malicious input data.