CVE-2004-1772 in sharutils
Summary
by MITRE
Stack-based buffer overflow in shar in GNU sharutils 4.2.1 allows local users to execute arbitrary code via a long -o command line argument.
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Analysis
by VulDB Data Team • 05/31/2019
The vulnerability described in CVE-2004-1772 represents a critical stack-based buffer overflow flaw within the shar utility component of GNU sharutils version 4.2.1. This issue resides in the command-line argument processing mechanism where the -o option fails to properly validate input length, creating an exploitable condition that can be leveraged by local attackers to execute arbitrary code with elevated privileges. The shar utility is designed to create shell archives containing multiple files, making it a common tool for packaging and distributing software components within Unix-like systems. The buffer overflow occurs when the program processes excessively long command line arguments, specifically targeting the -o parameter that specifies the output file name, allowing attackers to overwrite adjacent stack memory locations.
The technical exploitation of this vulnerability follows a classic stack-based buffer overflow pattern where insufficient bounds checking permits an attacker to overwrite the return address and other critical stack variables. When a local user provides a command line argument exceeding the allocated buffer size for the -o parameter, the program continues writing beyond the intended memory boundaries, potentially corrupting the stack frame and enabling code execution control. This flaw falls under the CWE-121 category of stack-based buffer overflow, which is categorized as a fundamental memory safety issue that has been consistently identified as a primary attack vector in numerous security incidents. The vulnerability is particularly concerning because it requires no network connectivity and can be exploited through local system access, making it a significant concern for system administrators who must ensure proper input validation across all command-line utilities.
From an operational impact perspective, this vulnerability creates a severe security risk for systems running GNU sharutils 4.2.1, as local users can escalate their privileges and execute malicious code with the same permissions as the shar utility process. The attack surface is expanded through the use of the shar utility in automated scripts, system maintenance tasks, and file distribution processes where command-line arguments may be constructed from untrusted input sources. The vulnerability's exploitation aligns with ATT&CK technique T1068 which covers 'Exploitation for Privilege Escalation', and T1059 which covers 'Command and Scripting Interpreter' as attackers can leverage the compromised utility to execute arbitrary commands. Systems that frequently use the shar utility for packaging and distribution activities are particularly at risk, as this vulnerability could be exploited through compromised user accounts or during routine system administration tasks.
Mitigation strategies for CVE-2004-1772 should prioritize immediate patching of GNU sharutils to version 4.2.2 or later, which contains the necessary input validation fixes for the buffer overflow condition. System administrators should implement strict input validation for all command-line arguments, particularly those that directly influence file operations and output destinations. The principle of least privilege should be enforced by ensuring that the shar utility runs with minimal required permissions and that users have restricted access to its functionality. Additional defensive measures include monitoring for unusual command-line argument patterns, implementing runtime protections such as stack canaries, and conducting regular security audits of system utilities to identify similar buffer overflow vulnerabilities. Organizations should also consider implementing application whitelisting policies that restrict execution of potentially vulnerable utilities to known good configurations and regularly updating their security tooling to detect and prevent exploitation attempts targeting this specific vulnerability class.