CVE-2016-9442 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 memory corruption in certain conditions via a crafted HTML page.
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Analysis
by VulDB Data Team • 10/05/2022
The vulnerability identified as CVE-2016-9442 resides within the w3m web browser implementation, specifically in the Tatsuya Kinoshita fork version prior to 0.5.3-31. This represents a critical memory corruption flaw that enables remote attackers to execute arbitrary code through maliciously crafted HTML content. The vulnerability stems from insufficient input validation and memory management within the browser's HTML parsing engine, creating a pathway for attackers to manipulate memory structures and potentially gain unauthorized system access.
This memory corruption vulnerability operates through improper handling of malformed HTML elements, particularly when processing certain combinations of tags, attributes, and embedded content. The flaw manifests when the browser encounters specific sequences in HTML documents that trigger buffer overflows or use-after-free conditions within the w3m rendering engine. Attackers can exploit this by crafting HTML pages that contain carefully constructed elements designed to overwhelm or mismanage memory allocation patterns. The vulnerability is classified under CWE-121, which deals with stack-based buffer overflow conditions, and potentially CWE-122 for heap-based buffer overflows, depending on the specific memory corruption mechanism triggered.
The operational impact of CVE-2016-9442 extends beyond simple browser compromise, as successful exploitation can lead to complete system takeover. Remote attackers can leverage this vulnerability to execute malicious code with the privileges of the affected user, potentially escalating to system-level access depending on the execution environment. The attack vector requires no special privileges from the attacker, making it particularly dangerous as it can be exploited through standard web browsing activities. This vulnerability directly maps to ATT&CK technique T1203, which involves exploiting web browsers for code execution, and T1068, which covers the exploitation of remote services through memory corruption vulnerabilities.
Mitigation strategies for CVE-2016-9442 primarily involve immediate patching of the w3m browser to version 0.5.3-31 or later, which contains the necessary memory management fixes and input validation improvements. Organizations should implement network-level protections including web filtering and content inspection to block potentially malicious HTML content. Browser hardening measures such as disabling JavaScript execution for untrusted sites and implementing strict content security policies can reduce the attack surface. Additionally, security monitoring should be enhanced to detect unusual memory access patterns or potential exploitation attempts. The vulnerability demonstrates the critical importance of regular security updates and proper input validation in preventing memory corruption exploits, aligning with industry best practices outlined in NIST SP 800-144 and OWASP Top Ten security guidelines for web application security.