CVE-2005-0758 in gzip
Summary
by MITRE
zgrep in gzip before 1.3.5 does not properly sanitize arguments, which allows local users to execute arbitrary commands via filenames that are injected into a sed script.
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Analysis
by VulDB Data Team • 06/01/2019
The vulnerability identified as CVE-2005-0758 affects the zgrep utility within gzip versions prior to 1.3.5, representing a critical command injection flaw that enables local attackers to execute arbitrary system commands. This issue stems from inadequate input sanitization within the zgrep implementation, specifically when processing filenames that are subsequently incorporated into sed scripts without proper validation or escaping mechanisms. The vulnerability exists at the intersection of shell command construction and argument handling, creating a pathway for malicious input to be interpreted as executable commands rather than mere data.
The technical exploitation occurs when zgrep processes filenames containing special shell characters that are not properly escaped or sanitized before being passed to sed for pattern matching operations. When a local user provides a crafted filename containing shell metacharacters such as semicolons, pipes, or command substitution operators, these characters are interpreted by the shell during sed script execution, allowing arbitrary command execution with the privileges of the user running zgrep. This represents a classic command injection vulnerability that aligns with CWE-77 and CWE-88, specifically targeting improper neutralization of special elements used in shell commands.
The operational impact of this vulnerability extends beyond simple privilege escalation as it provides attackers with a mechanism to execute arbitrary code on systems where gzip is installed and accessible to local users. The vulnerability is particularly concerning because it operates within a utility that is commonly used for searching compressed files, making it a potential vector for privilege escalation attacks or persistent backdoor establishment. Attackers can leverage this flaw to execute commands with the same privileges as the user running zgrep, potentially leading to system compromise, data exfiltration, or further exploitation of the compromised system.
Security practitioners should implement immediate mitigations including updating gzip to version 1.3.5 or later, which contains proper argument sanitization and escaping mechanisms. Additionally, system administrators should review and restrict access to zgrep and related gzip utilities where possible, particularly in multi-user environments where local privilege escalation risks are heightened. The remediation approach should also include monitoring for suspicious usage patterns and implementing proper input validation at the application level to prevent similar vulnerabilities in other utilities that may be susceptible to shell injection attacks. This vulnerability serves as a reminder of the critical importance of proper input sanitization and the potential consequences of inadequate shell command construction in system utilities.