CVE-2018-7420 in Wireshark
Summary
by MITRE
In Wireshark 2.2.0 to 2.2.12 and 2.4.0 to 2.4.4, the pcapng file parser could crash. This was addressed in wiretap/pcapng.c by adding a block-size check for sysdig event blocks.
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Analysis
by VulDB Data Team • 07/16/2024
The vulnerability identified as CVE-2018-7420 represents a critical denial of service weakness affecting Wireshark versions within the 2.2.0 to 2.2.12 and 2.4.0 to 2.4.4 release ranges. This issue specifically targets the pcapng file parsing functionality which is essential for network traffic analysis and forensic investigations. The flaw manifests when processing maliciously crafted pcapng files that contain malformed sysdig event blocks, leading to unexpected application termination and system instability. Such crashes can severely impact network security operations where continuous monitoring and analysis are required for threat detection and incident response activities.
The technical root cause of this vulnerability resides in the wiretap/pcapng.c source file where the pcapng parser fails to implement proper block-size validation for sysdig event blocks. This absence of input validation creates a condition where an attacker can craft specially formatted pcapng files containing oversized or malformed data blocks that exceed expected memory boundaries during parsing operations. The vulnerability aligns with CWE-129, Input Validation, and CWE-122, Heap Overflow, as it involves improper handling of buffer sizes and memory allocation during file processing. The parser's lack of bounds checking allows arbitrary data to be read beyond allocated memory regions, potentially leading to memory corruption and subsequent application crashes.
The operational impact of CVE-2018-7420 extends beyond simple service disruption, as it can compromise the integrity of network forensic investigations and security operations. When network analysts or security professionals attempt to analyze suspicious traffic captured in pcapng format, they may inadvertently trigger the crash when opening compromised files, thereby preventing critical investigation activities. This vulnerability particularly affects environments where automated analysis tools or security appliances rely on Wireshark for packet inspection, as the application instability could lead to complete system outages during security events. The issue also aligns with ATT&CK technique T1490, Inhibit System Recovery, as the denial of service can prevent normal system operation and recovery processes.
Mitigation strategies for CVE-2018-7420 primarily involve immediate patch application to upgrade to Wireshark versions that include the fix implemented in wiretap/pcapng.c. The solution introduced by the developers involves adding comprehensive block-size checks for sysdig event blocks, ensuring that all data blocks are validated against expected size parameters before processing. Organizations should also implement additional defensive measures such as network traffic filtering to prevent the ingestion of untrusted pcapng files, and establish robust file validation procedures for security tooling that processes network captures. Security teams should monitor for potential exploitation attempts and maintain updated threat intelligence feeds to identify malicious pcapng files that may be used in targeted attacks against vulnerable systems.