CVE-2016-9375 in Wireshark
Summary
by MITRE
In Wireshark 2.2.0 to 2.2.1 and 2.0.0 to 2.0.7, the DTN dissector could go into an infinite loop, triggered by network traffic or a capture file. This was addressed in epan/dissectors/packet-dtn.c by checking whether SDNV evaluation was successful.
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Analysis
by VulDB Data Team • 10/04/2022
The vulnerability identified as CVE-2016-9375 represents a critical denial of service flaw within Wireshark network protocol analyzer versions 2.0.0 through 2.0.7 and 2.2.0 through 2.2.1. This issue specifically affects the Delay Tolerant Networking (DTN) dissector component that processes and interprets network traffic according to the DTN protocol standards. The flaw manifests as an infinite loop condition that can be triggered by either malformed network packets or specially crafted capture files, potentially causing the application to consume excessive CPU resources and become unresponsive. The vulnerability stems from improper handling of SDNV (Simple Dynamic Number Variable) encoding within the DTN protocol implementation, where the dissector fails to validate the success of SDNV evaluation before proceeding with further processing operations. This type of vulnerability falls under CWE-835, which specifically addresses infinite loops or iterations without proper termination conditions, making it a classic example of a denial of service through resource exhaustion.
The operational impact of this vulnerability extends beyond simple application instability to potentially compromise network monitoring capabilities and forensic analysis operations. When exploited, the infinite loop causes Wireshark to become unresponsive, effectively rendering the network analysis tool unusable for network administrators, security analysts, and incident responders who rely on it for traffic inspection and troubleshooting. The vulnerability is particularly concerning because it can be triggered through passive network monitoring scenarios where an attacker simply needs to send malformed DTN packets to a system running the vulnerable Wireshark version, or by opening a malicious capture file that contains crafted DTN data structures. This makes the attack vector both accessible and difficult to detect, as the malicious traffic might appear legitimate to network monitoring systems that do not immediately recognize the malformed DTN sequences as a threat. The issue aligns with ATT&CK technique T1499.001, which covers network denial of service attacks, and specifically targets the availability aspect of the CIA triad by disrupting network analysis operations.
The remediation for CVE-2016-9375 involved implementing proper validation checks within the packet-dtn.c file to ensure that SDNV evaluation operations complete successfully before the dissector continues processing subsequent data elements. This fix aligns with the principle of defensive programming and input validation, which are fundamental requirements in secure coding practices. The solution demonstrates the importance of proper error handling in protocol dissector implementations where malformed input data can cause cascading failures. Network security professionals should prioritize updating affected Wireshark installations to versions 2.0.8 or 2.2.2 and later, which contain the patched dissector implementation. Organizations relying on Wireshark for network monitoring should also implement network segmentation and traffic filtering to prevent potentially malicious DTN traffic from reaching systems running vulnerable versions. The vulnerability serves as a reminder of the critical importance of validating all input data in network protocol analyzers, particularly when processing protocols that use variable-length encoding schemes like SDNV, which require careful handling to prevent exploitation through malformed data sequences.