CVE-2001-0700 in w3m
Summary
by MITRE
Buffer overflow in w3m 0.2.1 and earlier allows a remote attacker to execute arbitrary code via a long base64 encoded MIME header.
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Analysis
by VulDB Data Team • 08/21/2024
The vulnerability identified as CVE-2001-0700 represents a critical buffer overflow flaw in the w3m web browser version 0.2.1 and earlier releases. This issue specifically affects the handling of base64 encoded MIME headers within the application's parsing mechanism, creating a potential remote code execution vector that could be exploited by malicious actors. The w3m browser, being a text-based web browser commonly used in terminal environments and server configurations, presents a significant security risk when vulnerable versions are deployed in production systems.
The technical flaw manifests when the w3m application processes email messages or web content containing excessively long base64 encoded MIME headers. The application fails to properly validate the length of these headers before attempting to decode and process them, leading to a buffer overflow condition in memory. This overflow occurs because the software allocates a fixed-size buffer to store the decoded base64 content but does not perform adequate bounds checking to prevent data from exceeding the allocated memory space. The vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-125, which covers out-of-bounds read vulnerabilities that can lead to memory corruption.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it enables remote code execution capabilities for attackers who can craft malicious MIME headers. When a user accesses content containing the specially crafted header, the buffer overflow can be exploited to overwrite critical memory locations including return addresses and program execution flow. This allows attackers to inject and execute arbitrary code with the privileges of the w3m process, potentially leading to complete system compromise. The vulnerability is particularly concerning in server environments where w3m might be used to process email or web content from untrusted sources, as it could be leveraged for privilege escalation or persistent access to compromised systems.
From a threat modeling perspective, this vulnerability maps to several ATT&CK techniques including T1059 for command and scripting interpreter usage and T1068 for exploit for privilege escalation. The attack surface is broadened by the fact that w3m is commonly used in automated systems and server configurations, making it a valuable target for adversaries seeking persistent access. Organizations using vulnerable versions should consider immediate remediation through patch updates, as well as network segmentation and monitoring to detect potential exploitation attempts. The vulnerability also highlights the importance of proper input validation and bounds checking in applications processing untrusted data, particularly in security-sensitive environments where text-based browsers are employed for content handling. System administrators should implement comprehensive monitoring for unusual memory access patterns and ensure that all instances of w3m are updated to versions that address this specific buffer overflow condition.