CVE-2016-9425 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.
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Analysis
by VulDB Data Team • 10/05/2022
The vulnerability identified as CVE-2016-9425 represents a critical heap-based buffer overflow flaw within the w3m web browser fork developed by Tatsuya Kinoshita. This security issue affects versions prior to 0.5.3-31 and demonstrates the dangerous potential of memory corruption vulnerabilities in web browsing applications. The flaw specifically resides within the addMultirowsForm function, which processes HTML form elements containing multiple rows of data. When a maliciously crafted HTML page is processed by the vulnerable w3m version, the buffer overflow condition can be triggered, potentially leading to system compromise. The vulnerability operates at the intersection of memory management errors and web content processing, making it particularly concerning for users who encounter untrusted web content.
The technical nature of this vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions where insufficient bounds checking allows attackers to write beyond allocated memory boundaries. The addMultirowsForm function appears to inadequately validate input parameters when processing HTML form elements with multiple row structures, creating an opportunity for attackers to manipulate heap memory layout. This type of vulnerability typically occurs when the application allocates a fixed-size buffer on the heap and subsequently writes data that exceeds this boundary without proper validation. The flaw can be exploited through remote code execution if attackers can control the memory layout sufficiently to inject and execute malicious code, or at minimum cause a denial of service through application crashes.
Operational impact assessment reveals that this vulnerability poses significant risk to users of the affected w3m fork, particularly in environments where web browsing is conducted without proper sandboxing or network isolation. The denial of service aspect can be leveraged by attackers to disrupt service availability, while the potential for remote code execution creates opportunities for complete system compromise. Attackers could craft HTML pages containing malicious form elements that trigger the buffer overflow when rendered by the vulnerable browser, potentially leading to privilege escalation or persistent access. The vulnerability affects both server and client environments where w3m is used, making it relevant to web application security testing and penetration testing activities. Organizations relying on w3m for web browsing or automated content processing should consider this vulnerability as a high-priority threat requiring immediate remediation.
Mitigation strategies for CVE-2016-9425 should prioritize immediate patching of affected w3m installations to version 0.5.3-31 or later, which contains the necessary fixes for the heap-based buffer overflow condition. System administrators should implement network segmentation and web filtering controls to limit exposure to potentially malicious web content, particularly in environments where w3m is deployed. The implementation of application whitelisting and sandboxing measures can provide additional defense-in-depth layers to prevent exploitation attempts. Security monitoring should include detection of unusual memory allocation patterns or process crashes that may indicate exploitation attempts. Organizations should also conduct vulnerability assessments to identify any other installations of the affected w3m fork that may be present in their environment. The remediation process should include thorough testing of patched versions to ensure that the fix does not introduce regressions in functionality while maintaining the security improvements. This vulnerability also highlights the importance of regular security updates and proper vulnerability management processes within software development and deployment lifecycle practices.