CVE-2008-3432 in Vim
Summary
by MITRE
Heap-based buffer overflow in the mch_expand_wildcards function in os_unix.c in Vim 6.2 and 6.3 allows user-assisted attackers to execute arbitrary code via shell metacharacters in filenames, as demonstrated by the netrw.v3 test case.
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Analysis
by VulDB Data Team • 01/03/2025
The vulnerability identified as CVE-2008-3432 represents a critical heap-based buffer overflow within the Vim text editor version 6.2 and 6.3. This flaw exists in the mch_expand_wildcards function located in the os_unix.c source file, which handles wildcard expansion on unix-like systems. The vulnerability specifically manifests when processing filenames containing shell metacharacters, creating a condition where attacker-controlled input can overwrite adjacent memory locations in the heap allocation. The attack vector requires user assistance, meaning an attacker must convince a victim to interact with a maliciously crafted filename or directory structure, typically through network file sharing or collaborative editing scenarios where the netrw.v3 test case demonstrates the exploit mechanism.
The technical exploitation of this vulnerability leverages the improper handling of shell metacharacters within the filename expansion process. When Vim processes wildcards in filenames, the mch_expand_wildcards function fails to properly validate or sanitize input containing special shell characters such as semicolons, pipes, or backticks. This inadequate input validation allows attackers to inject shell commands that get executed during the wildcard expansion phase, effectively bypassing normal input sanitization mechanisms. The heap-based nature of the overflow means that memory corruption occurs in the program's heap space rather than stack space, making exploitation more complex but still highly effective. The vulnerability directly maps to CWE-121, which describes heap-based buffer overflow conditions, and represents a classic example of improper input validation leading to arbitrary code execution.
The operational impact of this vulnerability extends beyond simple code execution, as it can enable attackers to gain full control of the affected system when Vim is used in privileged contexts. Since Vim is commonly used for editing system configuration files, log files, and other sensitive data, an attacker who successfully exploits this vulnerability could potentially escalate privileges, access confidential information, or establish persistent access to the target system. The netrw.v3 test case specifically demonstrates how network-based file operations can trigger this vulnerability, making it particularly dangerous in collaborative environments where users might unknowingly open malicious files shared over networks. This vulnerability also aligns with ATT&CK technique T1059.007, which covers the use of command and scripting interpreters, as the exploit leverages shell command injection within the Vim environment.
Mitigation strategies for CVE-2008-3432 should prioritize immediate patching of affected Vim versions to the latest stable releases, which contain proper input validation and memory management fixes. Organizations should implement network segmentation and access controls to limit exposure of systems running vulnerable versions of Vim, particularly those used in shared or collaborative environments. Input sanitization measures should be implemented at the application level to prevent shell metacharacter injection, and system administrators should monitor for unusual file access patterns that might indicate exploitation attempts. Additionally, security awareness training should emphasize the dangers of opening untrusted files, particularly in collaborative editing environments where network-based file sharing occurs. The vulnerability highlights the importance of proper memory management and input validation in text processing applications, serving as a reminder of the critical security implications when handling user-supplied data in system utilities.