CVE-2001-0961 in MOST
Summary
by MITRE
Buffer overflow in tab expansion capability of the most program allows local or remote attackers to execute arbitrary code via a malformed file that is viewed with most.
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Analysis
by VulDB Data Team • 04/29/2019
The vulnerability identified as CVE-2001-0961 represents a critical buffer overflow flaw within the tab expansion functionality of the most program, a widely used text viewer in Unix-like operating systems. This vulnerability resides in the core processing logic that handles tab character expansion when displaying text files, creating a pathway for malicious code execution through carefully crafted input files. The most program, which serves as a fundamental tool for viewing text files in many Unix environments, becomes a potential attack vector when processing files containing malformed tab sequences that exceed allocated buffer boundaries.
The technical implementation of this buffer overflow stems from inadequate input validation and bounds checking within the tab expansion algorithm. When the most program encounters a file with malformed tab characters or excessive tab sequences, the software fails to properly validate the length of tab expansions against allocated memory buffers. This oversight allows attackers to craft files containing specially constructed tab characters that, when processed by most, trigger memory corruption. The vulnerability operates at the application layer and can be exploited through both local and remote attack vectors, making it particularly dangerous in networked environments where users might unknowingly view maliciously crafted files.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it enables attackers to execute arbitrary code with the privileges of the user running the most program. This capability can lead to complete system compromise, especially when the program is executed with elevated privileges or when users regularly view files from untrusted sources. The vulnerability affects systems where most is installed and commonly used, including various Unix distributions and Linux systems that rely on this text viewing utility. Attackers can leverage this weakness to gain unauthorized access, install backdoors, or perform other malicious activities without requiring direct system access or authentication.
Mitigation strategies for CVE-2001-0961 should prioritize immediate patching of affected systems, as this vulnerability has been widely exploited in the wild since its discovery. System administrators should ensure that all instances of the most program are updated to versions that include proper input validation and buffer size enforcement. Additionally, implementing file validation procedures and restricting user access to potentially malicious files can significantly reduce the attack surface. The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and corresponds to techniques documented in the MITRE ATT&CK framework under execution and privilege escalation domains. Organizations should also consider implementing network segmentation and monitoring for suspicious file viewing activities to detect potential exploitation attempts. Regular security audits and vulnerability assessments should include verification of most program installations to ensure that all systems remain protected against this and similar buffer overflow vulnerabilities.