CVE-2015-4035 in xzgrep
Summary
by MITRE
scripts/xzgrep.in in xzgrep 5.2.x before 5.2.0, before 5.0.0 does not properly process file names containing semicolons, which allows remote attackers to execute arbitrary code by having a user run xzgrep on a crafted file name.
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Analysis
by VulDB Data Team • 12/14/2022
The vulnerability identified as CVE-2015-4035 represents a critical command injection flaw in the xzgrep utility that affects versions prior to 5.2.0 and 5.0.0. This issue resides within the script file scripts/xzgrep.in which processes file names containing semicolons without proper sanitization, creating an avenue for malicious code execution through crafted file names. The vulnerability operates at the command-line interface level where the utility fails to properly escape or validate input parameters, allowing attackers to inject shell commands that get executed when users run xzgrep on maliciously crafted file names. The flaw demonstrates a classic security oversight in shell argument handling where special characters are not adequately sanitized, directly correlating to CWE-78, which describes improper neutralization of special elements used in OS commands.
The technical exploitation of this vulnerability relies on the inherent behavior of shell command execution where semicolons are interpreted as command separators, enabling attackers to append malicious commands to legitimate file names. When a user executes xzgrep on a file name containing a semicolon followed by malicious shell commands, the system processes these commands as part of the execution flow rather than treating them as literal file name characters. This vulnerability falls under the ATT&CK technique T1059.001, which covers command and scripting interpreter, specifically targeting the execution of shell commands through improper input handling. The attack vector typically involves social engineering where users are tricked into running xzgrep on maliciously crafted file names, making it particularly dangerous in environments where users frequently process untrusted file content.
The operational impact of CVE-2015-4035 extends beyond simple code execution, as it can potentially lead to complete system compromise when attackers leverage this vulnerability in conjunction with other attack vectors. Organizations using affected versions of xzgrep face significant risk when processing files from untrusted sources, as a single malicious file can result in arbitrary code execution with the privileges of the user running xzgrep. This vulnerability is particularly concerning in automated processing environments, backup systems, and file analysis tools that might automatically invoke xzgrep on files without user intervention. The vulnerability affects the broader xz-utils package ecosystem and demonstrates how seemingly benign script processing can create critical security gaps, especially in utilities that handle file names and system commands in an unsecured manner.
Mitigation strategies for CVE-2015-4035 primarily involve upgrading to xz-utils version 5.2.0 or later where the vulnerability has been patched. System administrators should implement immediate patch management protocols to ensure all affected systems are updated and remove or quarantine any potentially malicious files that might have been processed through the vulnerable utility. Additional protective measures include implementing strict file name validation in automated processing pipelines, using secure file handling practices that prevent untrusted file names from being passed to xzgrep, and educating users about the dangers of processing untrusted files. Organizations should also consider implementing network-based intrusion detection systems that can identify potential exploitation attempts and monitor for suspicious command execution patterns. The vulnerability serves as a reminder of the importance of proper input validation and secure coding practices, particularly in utilities that interface directly with shell commands and file system operations, emphasizing the need for comprehensive security testing of command-line utilities in security-sensitive environments.