CVE-2004-0548 in Aspell
Summary
by MITRE
Multiple stack-based buffer overflows in the word-list-compress functionality in compress.c for Aspell allow local users to execute arbitrary code via a long entry in the wordlist that is not properly handled when using the (1) "c" compress option or (2) "d" decompress option.
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Analysis
by VulDB Data Team • 10/26/2024
The vulnerability described in CVE-2004-0548 represents a critical stack-based buffer overflow in the Aspell spell-checking utility's compression functionality. This flaw exists within the compress.c source file where the word-list-compress functionality processes user-provided input without adequate bounds checking. The vulnerability specifically affects the handling of wordlist entries when utilizing either the "c" compress option or the "d" decompress option, creating a pathway for malicious code execution. The issue stems from insufficient input validation mechanisms that fail to properly manage the size of entries within the wordlist, allowing attackers to overflow the allocated stack buffer and potentially overwrite adjacent memory regions.
The technical exploitation of this vulnerability occurs through careful manipulation of wordlist entries that exceed the expected buffer size limits. When Aspell processes a wordlist containing an excessively long entry, the compression or decompression routines fail to validate the input length before copying data to the fixed-size stack buffer. This allows an attacker to overwrite the return address or other critical stack variables, effectively gaining control over the program execution flow. The vulnerability is classified as a stack-based buffer overflow, which aligns with CWE-121 and CWE-122 categories that specifically address buffer overflow conditions in stack memory. The attack vector is local since it requires the ability to modify the wordlist files that Aspell processes, making it particularly concerning for systems where users can influence spell-checking data.
The operational impact of CVE-2004-0548 extends beyond simple code execution, as it can lead to complete system compromise when exploited by local attackers. The vulnerability enables privilege escalation in scenarios where Aspell is executed with elevated permissions, potentially allowing attackers to gain root access on affected systems. This makes the flaw particularly dangerous in multi-user environments where spell-checking utilities might be used by untrusted users or where Aspell is employed in automated processes. The vulnerability affects systems running older versions of Aspell where the compression functionality was not properly hardened against malicious input. The attack model aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as successful exploitation could enable attackers to execute arbitrary commands through the compromised spell-checking utility.
Mitigation strategies for this vulnerability should include immediate patching of Aspell to versions that properly validate input lengths before processing compression or decompression operations. System administrators should implement strict input validation controls and consider disabling unnecessary compression functionality when it is not required for system operations. The recommended approach involves applying the vendor-supplied security patches that address the buffer overflow conditions in the compress.c file by implementing proper bounds checking and input sanitization. Additionally, organizations should conduct regular security audits of their spell-checking and text processing utilities to identify similar vulnerabilities that might exist in other components of their software stack. Network segmentation and privilege separation measures can further reduce the impact of potential exploitation by limiting the attack surface and preventing unauthorized modifications to wordlist files that could trigger the vulnerability.