CVE-2015-8716 in Wireshark
Summary
by MITRE
The init_t38_info_conv function in epan/dissectors/packet-t38.c in the T.38 dissector in Wireshark 1.12.x before 1.12.9 does not ensure that a conversation exists, which allows remote attackers to cause a denial of service (application crash) via a crafted packet.
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Analysis
by VulDB Data Team • 07/02/2022
The vulnerability identified as CVE-2015-8716 resides within the T.38 dissector component of Wireshark, specifically in the init_t38_info_conv function located in epan/dissectors/packet-t38.c. This flaw represents a classic null pointer dereference issue that occurs when the application attempts to process network packets without proper validation of conversation context. The T.38 protocol is used for fax transmission over IP networks, and Wireshark's dissector is responsible for parsing and analyzing these packets during network traffic analysis. When a malformed or crafted packet is processed, the dissector fails to verify that a conversation object exists before attempting to access its properties, leading to an application crash that constitutes a denial of service condition. This vulnerability is particularly concerning because it can be exploited remotely through network traffic analysis, making it a significant threat to network monitoring and security analysis systems that rely on Wireshark for packet inspection.
The technical implementation of this vulnerability stems from inadequate input validation within the T.38 dissector logic. The init_t38_info_conv function assumes that a conversation context will always be present when processing T.38 packets, but this assumption fails when encountering malformed packets that do not properly establish conversation state. This type of flaw aligns with CWE-476, which categorizes null pointer dereference vulnerabilities as a common weakness in software design. The absence of proper conversation existence checks creates a path where an attacker can craft specific packet payloads that trigger the application to attempt accessing memory locations that have not been allocated or initialized. The vulnerability manifests as an application crash rather than arbitrary code execution, but the denial of service impact is severe enough to disrupt network monitoring operations and potentially allow attackers to cause availability issues for security infrastructure.
From an operational perspective, this vulnerability poses significant risks to organizations that depend on Wireshark for network security monitoring, incident response, and troubleshooting activities. Network security analysts and administrators who use Wireshark to analyze traffic containing T.38 fax communications are vulnerable to remote denial of service attacks that could disrupt their monitoring capabilities. The attack vector is particularly dangerous because it requires no authentication or special privileges beyond the ability to send network packets to the target system. The vulnerability affects Wireshark versions 1.12.x prior to 1.12.9, making it a widespread issue across many network security monitoring deployments that may not have been updated to the patched versions. The impact extends beyond simple application crashes, as the disruption of network analysis tools can compromise an organization's ability to detect and respond to other security incidents, creating cascading effects on overall security posture.
Mitigation strategies for CVE-2015-8716 primarily focus on immediate software updates and deployment of patched versions of Wireshark. Organizations should prioritize updating to Wireshark 1.12.9 or later versions that contain the necessary fixes for this vulnerability. The patch addresses the root cause by implementing proper conversation existence validation before attempting to access conversation properties. Network administrators should also consider implementing additional defensive measures such as network segmentation to limit exposure, deploying packet filtering rules to prevent malformed T.38 packets from reaching monitoring systems, and implementing intrusion detection systems that can identify and alert on suspicious packet patterns. From an ATT&CK framework perspective, this vulnerability maps to the T1499.004 technique related to network denial of service, and the T1566.001 technique for social engineering through network traffic manipulation. Security teams should also consider implementing monitoring for unusual application crash patterns and ensure that backup network analysis tools are available to maintain operational continuity during potential exploitation attempts.