CVE-2007-2953 in Vim
Summary
by MITRE
Format string vulnerability in the helptags_one function in src/ex_cmds.c in Vim 6.4 and earlier, and 7.x up to 7.1, allows user-assisted remote attackers to execute arbitrary code via format string specifiers in a help-tags tag in a help file, related to the helptags command.
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Analysis
by VulDB Data Team • 07/23/2019
The vulnerability identified as CVE-2007-2953 represents a critical format string vulnerability within the Vim text editor that affects versions 6.4 and earlier, as well as 7.x versions up to 7.1. This flaw exists in the helptags_one function located in the src/ex_cmds.c source file, specifically when processing help-tags tags in help files. The vulnerability is particularly concerning because it enables user-assisted remote code execution through carefully crafted format string specifiers embedded within help file content, making it a significant threat to systems running vulnerable versions of Vim.
The technical nature of this vulnerability stems from improper handling of format strings in the helptags_one function, which processes help tags when the helptags command is executed. When Vim encounters help files containing maliciously crafted format specifiers, the application fails to properly validate or sanitize these inputs before using them in printf-like functions. This lack of input validation creates a classic format string vulnerability where attacker-controlled data can be interpreted as format specifiers, potentially leading to memory corruption, information disclosure, or arbitrary code execution. The vulnerability operates through the help file processing mechanism, where users or remote attackers can influence the content of help files that Vim subsequently processes, making it exploitable in scenarios where users might access untrusted help content.
The operational impact of this vulnerability extends beyond simple privilege escalation as it can be exploited remotely through user-assisted means, potentially allowing attackers to execute arbitrary code with the privileges of the user running Vim. The attack vector is particularly dangerous because it can be triggered through legitimate help file processing operations, making detection more challenging. Systems running vulnerable versions of Vim are at risk when users access help files from untrusted sources, including web-based help systems, shared repositories, or collaborative environments where help content might be modified by malicious actors. The vulnerability affects both local and remote exploitation scenarios, as attackers can craft help files that, when processed by Vim, trigger the format string vulnerability.
Mitigation strategies for CVE-2007-2953 primarily focus on immediate version updates to patched versions of Vim, as this vulnerability was addressed in subsequent releases. Organizations should prioritize updating their Vim installations to versions that contain proper input validation and format string handling fixes. Additionally, administrators should implement strict access controls on help file directories and ensure that help content is only sourced from trusted repositories. The vulnerability aligns with CWE-134, which specifically addresses format string vulnerabilities where format strings are constructed from user-controlled data, and can be mapped to ATT&CK technique T1059.007 for execution through command-line interfaces. Security monitoring should include detection of unusual help file processing activities and potential format string exploitation attempts, particularly in environments where Vim is widely used for development or system administration tasks.