CVE-2016-9440 in w3m
Summary
by MITRE
An issue was discovered in the Tatsuya Kinoshita w3m fork before 0.5.3-31. w3m allows remote attackers to cause a denial of service (segmentation fault and crash) via a crafted HTML page.
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Analysis
by VulDB Data Team • 10/05/2022
The vulnerability identified as CVE-2016-9440 affects the w3m web browser implementation developed by Tatsuya Kinoshita, specifically in versions prior to 0.5.3-31. This represents a critical denial of service flaw that demonstrates the inherent risks associated with web browser implementations that fail to properly validate input data. The vulnerability stems from insufficient sanitization of HTML content, allowing malicious actors to craft specific web pages that trigger segmentation faults within the application. Such flaws are particularly concerning in browser environments where users expect to interact with arbitrary web content without compromising system stability.
The technical nature of this vulnerability aligns with CWE-121, which describes buffer overflow conditions that can lead to memory corruption and system crashes. The flaw manifests when the w3m browser encounters specially crafted HTML elements that cause memory access violations during parsing operations. The segmentation fault occurs because the application does not properly handle malformed HTML structures, particularly those involving nested elements or malformed attributes that exceed expected memory boundaries. This type of vulnerability falls under the category of memory safety issues that have been extensively documented in the cybersecurity community as primary attack vectors for remote exploitation.
From an operational perspective, this vulnerability presents significant risks to organizations relying on w3m for web browsing or as part of automated systems. The remote attack vector means that users can be compromised simply by visiting malicious websites or clicking on links in email messages without any additional interaction required from the victim. The impact extends beyond individual user sessions to potentially affect automated systems that depend on w3m for web content retrieval or processing. Attackers can leverage this flaw to disrupt services, cause system instability, or potentially use it as a stepping stone for more sophisticated attacks that might exploit additional vulnerabilities within the same system.
The mitigation strategy for CVE-2016-9440 primarily involves upgrading to w3m version 0.5.3-31 or later, which includes proper input validation and memory handling fixes. Organizations should implement immediate patch management procedures to address this vulnerability across all affected systems. Additionally, network administrators should consider implementing web filtering solutions that can detect and block malicious HTML content before it reaches vulnerable systems. The vulnerability also highlights the importance of input sanitization practices in web browser implementations, aligning with ATT&CK technique T1059.007 for command and scripting interpreter execution and T1499.004 for network disruption. Security teams should conduct regular vulnerability assessments to identify similar issues in other browser implementations and ensure that proper security controls are in place to prevent exploitation of similar memory corruption vulnerabilities in the broader software ecosystem.