CVE-2002-0178 in sharutils
Summary
by MITRE
uudecode, as available in the sharutils package before 4.2.1, does not check whether the filename of the uudecoded file is a pipe or symbolic link, which could allow attackers to overwrite files or execute commands.
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Analysis
by VulDB Data Team • 09/22/2025
The vulnerability identified as CVE-2002-0178 resides within the uudecode utility distributed with the sharutils package version 4.2.1 and earlier. This flaw represents a critical security issue that stems from inadequate input validation during the file decoding process. The vulnerability specifically affects how uudecode handles file naming conventions when processing uuencoded data, creating potential pathways for malicious exploitation.
The technical flaw manifests in the absence of proper validation checks for file destinations during uudecode operations. When uudecode processes encoded data, it does not verify whether the target filename corresponds to a pipe or symbolic link before creating or overwriting files. This oversight allows attackers to craft malicious uuencoded content that specifies filenames pointing to special file types such as named pipes or symbolic links. The vulnerability directly maps to CWE-59, which describes improper handling of symbolic links, and CWE-22, concerning improper limitation of a pathname to a restricted directory.
The operational impact of this vulnerability extends beyond simple file overwriting capabilities. Attackers can leverage this weakness to execute arbitrary commands on vulnerable systems by carefully crafting uuencoded content that creates symbolic links pointing to system-critical files or executables. When the uudecode utility attempts to write to these targets, it may inadvertently execute code or overwrite critical system components. This represents a significant privilege escalation vector that aligns with ATT&CK technique T1059.001 for command and scripting interpreter and T1068 for exploit for privilege escalation.
The security implications of CVE-2002-0178 are particularly severe in environments where users can submit uuencoded content for processing, such as in email systems, file transfer protocols, or collaborative development platforms. The vulnerability can be exploited through various attack vectors including social engineering, where attackers convince users to process malicious uuencoded files, or through automated systems that process untrusted content. Organizations using older versions of sharutils or similar packages remain at risk, as the flaw exists in the fundamental file handling mechanism of the utility. The vulnerability also demonstrates the importance of proper input validation and file system security practices, as it highlights how simple oversight in filename handling can lead to complex exploitation scenarios.
Mitigation strategies for this vulnerability include immediate upgrading to sharutils version 4.2.1 or later, which contains the necessary fixes for proper filename validation. System administrators should also implement additional security controls such as restricting uudecode execution permissions, implementing proper file system permissions, and employing content filtering mechanisms that can detect and prevent potentially malicious uuencoded content. Organizations should conduct comprehensive vulnerability assessments to identify systems running affected versions of sharutils and ensure proper patch management procedures are in place to prevent similar issues in other software components. The fix implemented in version 4.2.1 specifically addresses the missing validation checks and ensures that uudecode properly handles all file types before creating or overwriting files, thereby preventing the exploitation scenarios described in the vulnerability.