CVE-2018-14340 in Wireshark
Summary
by MITRE
In Wireshark 2.6.0 to 2.6.1, 2.4.0 to 2.4.7, and 2.2.0 to 2.2.15, dissectors that support zlib decompression could crash. This was addressed in epan/tvbuff_zlib.c by rejecting negative lengths to avoid a buffer over-read.
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Analysis
by VulDB Data Team • 04/18/2023
The vulnerability identified as CVE-2018-14340 represents a critical buffer over-read condition affecting multiple versions of the popular network protocol analyzer Wireshark. This flaw specifically impacts dissectors within Wireshark that handle zlib compressed data streams, creating a scenario where maliciously crafted network traffic could trigger unexpected program termination. The vulnerability affects versions 2.6.0 through 2.6.1, 2.4.0 through 2.4.7, and 2.2.0 through 2.2.15, indicating a widespread impact across several major release branches of the software. The root cause stems from inadequate input validation within the decompression handling code, particularly in the epan/tvbuff_zlib.c component that manages zlib decompression operations. This technical weakness allows attackers to craft packets containing malformed zlib compressed data with negative length values that bypass normal validation checks.
The operational impact of this vulnerability extends beyond simple application crashes, as it creates potential denial of service conditions that could disrupt network analysis operations. When Wireshark processes packets containing specially crafted zlib compressed data with negative lengths, the decompression routine attempts to allocate memory buffers based on these invalid parameters, leading to buffer over-read conditions. This type of vulnerability falls under CWE-129, which specifically addresses insufficient validation of length fields, and aligns with ATT&CK technique T1059.007 for command and scripting interpreter usage in network analysis contexts. Network security professionals relying on Wireshark for traffic inspection and forensic analysis could experience complete tool failure when encountering maliciously constructed packets, potentially compromising their ability to investigate network incidents or perform security monitoring tasks.
The fix implemented by the Wireshark development team addresses the core issue by adding explicit validation to reject negative length values before they can cause buffer over-read conditions. This defensive programming approach ensures that zlib decompression operations only proceed with valid, non-negative length parameters, thereby preventing the memory corruption that led to crashes. The mitigation strategy involves updating to patched versions of Wireshark where the epan/tvbuff_zlib.c module properly validates input parameters before processing zlib compressed data. Organizations should prioritize patching affected systems, as the vulnerability could be exploited in automated attack scenarios where network traffic analysis tools are targeted. Security operations teams should also implement monitoring for unusual network traffic patterns that might indicate exploitation attempts, particularly in environments where Wireshark is used for continuous network monitoring. The fix demonstrates proper input validation practices that align with secure coding guidelines and helps prevent similar issues in other decompression handling components within network analysis tools.