CVE-2015-8729 in Wireshark
Summary
by MITRE
The ascend_seek function in wiretap/ascendtext.c in the Ascend file parser in Wireshark 1.12.x before 1.12.9 and 2.0.x before 2.0.1 does not ensure the presence of a '\0' character at the end of a date string, which allows remote attackers to cause a denial of service (out-of-bounds read and application crash) via a crafted file.
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Analysis
by VulDB Data Team • 12/22/2024
The CVE-2015-8729 vulnerability resides within the Ascend file parser component of Wireshark, specifically in the ascend_seek function located in wiretap/ascendtext.c. This flaw affects versions 1.12.x prior to 1.12.9 and 2.0.x prior to 2.0.1, representing a critical denial of service vulnerability that can be exploited remotely. The vulnerability stems from insufficient input validation within the date string parsing logic, where the function fails to verify the presence of a null terminator character at the end of date strings. This oversight creates a condition where crafted malicious files can trigger memory access violations during file processing.
The technical implementation of this vulnerability involves a classic out-of-bounds read scenario where the ascend_seek function assumes the presence of a null character to properly terminate date strings. When processing Ascend text files, Wireshark's parser attempts to locate specific date patterns within the file content, but without proper bounds checking or null termination verification, the function can read beyond allocated memory boundaries. This behavior directly corresponds to CWE-129, which addresses improper validation of array index values, and CWE-125, which covers out-of-bounds read conditions. The vulnerability operates under the principle that untrusted input data should never be trusted without proper validation, a fundamental security principle that was violated in this implementation.
From an operational perspective, this vulnerability presents a significant risk to network security analysts and forensic investigators who rely on Wireshark for packet analysis. An attacker can craft a specially formatted Ascend text file that, when opened in Wireshark, will cause the application to crash immediately. The denial of service impact extends beyond simple application instability, as it can disrupt critical network monitoring operations and forensic investigations. The remote exploitation capability means that an attacker could potentially send malicious files to unsuspecting users through various attack vectors including email attachments, web downloads, or file sharing platforms. This vulnerability aligns with ATT&CK technique T1499.001, which covers network denial of service attacks, and represents a classic example of how seemingly benign file parsing operations can become attack vectors when proper input validation is absent.
The mitigation strategy for CVE-2015-8729 involves immediate patching of affected Wireshark versions to 1.12.9 or 2.0.1 respectively, which contain the necessary fixes to properly validate date string termination. Organizations should also implement defensive measures such as restricting file opening permissions for untrusted files and employing automated scanning tools to detect potentially malicious Ascend text files. Network administrators should consider implementing file type validation at network boundaries and establish procedures for handling suspicious file attachments. Additionally, security teams should conduct regular vulnerability assessments to identify similar input validation flaws in other network analysis tools and ensure that all third-party applications undergo proper security testing before deployment in production environments. The fix implemented by Wireshark developers specifically addresses the missing null terminator check and ensures proper bounds validation during date string processing, thereby preventing the out-of-bounds read conditions that led to the application crashes.