CVE-2016-4077 in Wireshark
Summary
by MITRE
epan/reassemble.c in TShark in Wireshark 2.0.x before 2.0.3 relies on incorrect special-case handling of truncated Tvb data structures, which allows remote attackers to cause a denial of service (use-after-free and application crash) via a crafted packet.
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Analysis
by VulDB Data Team • 07/26/2022
The vulnerability identified as CVE-2016-4077 represents a critical memory safety issue within the TShark packet analysis component of Wireshark version 2.0.x before 2.0.3. This flaw resides in the epan/reassemble.c file and specifically targets the handling of truncated Tvb (Temporary Virtual Buffer) data structures during packet reassembly operations. The issue stems from improper special-case handling logic that fails to properly validate buffer boundaries when processing fragmented network packets, creating a dangerous condition where memory access occurs after the buffer has been freed.
The technical implementation of this vulnerability exploits a use-after-free condition that occurs when TShark attempts to reassemble fragmented packets and encounters truncated data structures. When processing malformed packets that contain truncated buffer information, the reassembly logic does not adequately verify that the buffer remains valid before attempting to access its contents. This incorrect handling creates a scenario where the application may attempt to read from memory locations that have already been deallocated, leading to unpredictable behavior and system instability. The flaw specifically manifests when TShark encounters packets with malformed or incomplete data structures that trigger the special-case code path designed to handle truncated data, but the code fails to properly manage the memory lifecycle in these scenarios.
The operational impact of CVE-2016-4077 extends beyond simple denial of service to potentially enable more sophisticated attack vectors. Remote attackers can craft specifically designed packets that, when processed by the vulnerable Wireshark version, will trigger the use-after-free condition and cause the application to crash. This creates a reliable denial of service scenario where legitimate network monitoring operations are disrupted, potentially affecting network administrators who rely on TShark for traffic analysis. The vulnerability is particularly concerning in environments where automated network monitoring systems process untrusted network traffic, as attackers could exploit this weakness to continuously disrupt monitoring operations without requiring authentication or elevated privileges.
From a cybersecurity perspective, this vulnerability aligns with CWE-416, which describes the use of freed memory condition, and demonstrates the importance of proper memory management in network analysis tools. The ATT&CK framework categorizes this as a Denial of Service technique, specifically within the T1499.004 sub-technique related to Network Denial of Service. The vulnerability also reflects common weaknesses in network protocol analysis software where complex reassembly logic can introduce memory safety issues. Organizations using Wireshark for network monitoring should prioritize patching to version 2.0.3 or later, as this release contains the necessary fixes to properly handle truncated Tvb data structures and prevent the use-after-free conditions that lead to application crashes. The fix typically involves implementing proper bounds checking and ensuring that buffer validation occurs before any memory access operations, preventing the scenario where freed memory locations are accessed during packet reassembly processes.