CVE-2016-9429 in w3m
Summary
by MITRE
An issue was discovered in the Tatsuya Kinoshita w3m fork before 0.5.3-31. Buffer overflow in the formUpdateBuffer function in w3m allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a crafted HTML page.
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Analysis
by VulDB Data Team • 10/05/2022
The vulnerability identified as CVE-2016-9429 represents a critical buffer overflow condition within the w3m web browser fork developed by Tatsuya Kinoshita. This flaw exists in versions prior to 0.5.3-31 and specifically affects the formUpdateBuffer function which handles HTML form processing operations. The buffer overflow occurs when the application processes malformed HTML content, particularly in form elements, leading to memory corruption that can be exploited by remote attackers to compromise system integrity. This vulnerability falls under the CWE-121 buffer overflow category, which is classified as a critical weakness in memory management that allows attackers to overwrite adjacent memory locations.
The technical exploitation of this vulnerability involves crafting malicious HTML pages that trigger the buffer overflow within the formUpdateBuffer function. When the w3m browser encounters such malformed content, the insufficient bounds checking in the buffer management routine allows attackers to write beyond allocated memory boundaries. This memory corruption can result in unpredictable program behavior including application crashes that constitute a denial of service condition. However, the vulnerability's potential for remote code execution makes it particularly dangerous as attackers may be able to leverage the buffer overflow to inject and execute arbitrary code on the target system. The attack vector requires only that a user visit a malicious webpage, making this a significant threat in web browsing environments.
The operational impact of CVE-2016-9429 extends beyond simple service disruption to potentially enable full system compromise. The denial of service aspect affects availability by causing the w3m browser to crash and terminate unexpectedly, disrupting user access to web content. The remote code execution capability, while potentially difficult to exploit successfully, represents a severe threat that could allow attackers to gain unauthorized access to systems running vulnerable versions of the browser. This vulnerability is particularly concerning in environments where w3m is used as a terminal-based browser for web access, as it could provide attackers with persistent access to network resources. The ATT&CK framework categorizes this type of vulnerability under initial access and execution tactics, where attackers can use buffer overflow exploits to establish footholds in target systems.
Mitigation strategies for this vulnerability primarily involve upgrading to w3m version 0.5.3-31 or later, which contains the necessary patches to address the buffer overflow condition. System administrators should prioritize this update across all affected systems, particularly in environments where w3m is actively used for web browsing. Additional protective measures include implementing web content filtering solutions to block access to potentially malicious websites, deploying network-based intrusion detection systems to monitor for exploitation attempts, and configuring sandboxing mechanisms to limit the impact of potential successful attacks. Organizations should also consider implementing automated patch management systems to ensure timely deployment of security updates and maintain comprehensive vulnerability assessment programs to identify similar issues in other browser implementations. The vulnerability highlights the importance of proper input validation and memory management practices in preventing buffer overflow exploits that can lead to system compromise.