CVE-2016-9428 in w3m
Summary
by MITRE
An issue was discovered in the Tatsuya Kinoshita w3m fork before 0.5.3-31. Heap-based buffer overflow in the addMultirowsForm function in w3m allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a crafted HTML page.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 10/15/2024
The vulnerability identified as CVE-2016-9428 represents a critical heap-based buffer overflow flaw within the w3m web browser fork maintained by Tatsuya Kinoshita. This issue affects versions prior to 0.5.3-31 and resides within the addMultirowsForm function, which processes HTML content containing multi-row form elements. The vulnerability manifests when the browser encounters specially crafted HTML pages that trigger improper memory handling during form processing operations. The heap-based nature of this buffer overflow indicates that the flaw occurs in dynamically allocated memory regions, making it particularly dangerous as it can lead to memory corruption and unpredictable system behavior.
The technical implementation of this vulnerability stems from insufficient bounds checking within the addMultirowsForm function, which fails to properly validate the size and structure of multi-row form elements in HTML documents. When processing maliciously constructed HTML content, the function allocates memory buffers that are subsequently overflowed when attempting to store data exceeding the allocated space. This memory corruption can occur during the parsing and rendering of complex form structures, particularly when dealing with nested or improperly structured multi-row form elements. The vulnerability's exploitation potential is heightened by the fact that it can be triggered through web-based content, making it accessible to remote attackers who can craft specific HTML pages to exploit the flaw.
The operational impact of CVE-2016-9428 extends beyond simple denial of service conditions to potentially enable remote code execution capabilities. When successfully exploited, the buffer overflow can cause the w3m browser to crash or terminate unexpectedly, leading to service disruption for users. However, the more severe implications arise from the possibility of arbitrary code execution, which would allow attackers to gain control over the affected system. This vulnerability directly impacts the security posture of systems relying on w3m for web browsing, as it creates an attack surface that can be leveraged for unauthorized access, data exfiltration, or system compromise. The remote exploitability means that attackers do not require physical access to the target system, making this vulnerability particularly concerning for environments where w3m is deployed.
Mitigation strategies for this vulnerability center on immediate software updates to versions 0.5.3-31 or later, which contain the necessary patches to address the heap-based buffer overflow. System administrators should prioritize patch management activities to ensure all affected installations are updated promptly. Additionally, implementing network-level protections such as web application firewalls and content filtering systems can provide additional defense-in-depth measures. The vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and represents a classic example of improper input validation leading to memory corruption. From an ATT&CK framework perspective, this vulnerability maps to the T1203 and T1059 techniques, representing the use of malicious web content to achieve remote code execution and command execution through browser-based attacks. Organizations should also consider implementing sandboxing mechanisms and restricting web browsing capabilities to minimize potential exploitation impact, while maintaining regular security assessments to identify similar vulnerabilities in other browser implementations or web-based applications.