CVE-2011-1957 in Wireshark
Summary
by MITRE
The dissect_dcm_main function in epan/dissectors/packet-dcm.c in the DICOM dissector in Wireshark 1.2.x before 1.2.17 and 1.4.x before 1.4.7 allows remote attackers to cause a denial of service (infinite loop) via an invalid PDU length.
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Analysis
by VulDB Data Team • 11/08/2021
The vulnerability described in CVE-2011-1957 represents a critical denial of service flaw within the Wireshark network protocol analyzer software. This issue specifically affects the DICOM dissector component which is responsible for analyzing Digital Imaging and Communications in Medicine protocol traffic. The vulnerability exists in versions of Wireshark prior to 1.2.17 and 1.4.7, making it a significant concern for network security professionals who rely on Wireshark for network traffic analysis and forensic investigations. The flaw manifests when the dissect_dcm_main function encounters malformed DICOM protocol data units with invalid PDU lengths, creating a condition that can be exploited by remote attackers to disrupt normal network monitoring operations.
The technical nature of this vulnerability stems from inadequate input validation within the DICOM protocol dissector module. When Wireshark processes network packets containing DICOM data, the dissect_dcm_main function attempts to parse the protocol header information including the PDU length field. However, the function fails to properly validate the length parameter, particularly when it contains invalid or malformed values. This validation gap allows an attacker to craft specially crafted DICOM packets that contain incorrect PDU length specifications, causing the dissector to enter an infinite loop during packet processing. The infinite loop occurs because the parsing logic does not properly handle the boundary conditions that should terminate the parsing routine when encountering invalid data structures, leading to resource exhaustion and complete system unresponsiveness.
The operational impact of this vulnerability extends beyond simple service disruption, as it can severely compromise network monitoring capabilities and forensic analysis operations. Network security teams who depend on Wireshark for real-time traffic analysis and incident response may find their monitoring systems rendered useless when malicious actors exploit this vulnerability. The denial of service condition can persist for extended periods, potentially going unnoticed in large network environments where multiple monitoring points exist. This vulnerability particularly affects organizations that handle medical imaging data or networks that process DICOM traffic, as these environments often rely heavily on continuous monitoring for compliance and operational purposes. The vulnerability can be exploited remotely without requiring authentication, making it particularly dangerous in environments where network traffic is continuously analyzed.
Mitigation strategies for this vulnerability primarily involve upgrading to patched versions of Wireshark where the issue has been resolved through proper input validation and boundary checking. The fix implemented in versions 1.2.17 and 1.4.7 addresses the root cause by adding comprehensive validation of PDU length fields before processing, ensuring that invalid values trigger appropriate error handling rather than infinite loop conditions. Network administrators should also implement network segmentation and access controls to limit exposure to potentially malicious traffic, while monitoring for unusual patterns that might indicate exploitation attempts. Additionally, organizations should maintain updated threat intelligence feeds to identify potential exploitation attempts targeting this specific vulnerability. From a cybersecurity perspective, this vulnerability aligns with CWE-129, which describes improper validation of input boundaries, and maps to ATT&CK technique T1499.004 for network denial of service attacks. The vulnerability demonstrates the critical importance of input validation in protocol analysis software and the potential for seemingly minor parsing flaws to result in significant operational disruptions.