CVE-2008-4636 in yast2-backup
Summary
by MITRE
yast2-backup 2.14.2 through 2.16.6 on SUSE Linux and Novell Linux allows local users to gain privileges via shell metacharacters in filenames used by the backup process.
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Analysis
by VulDB Data Team • 05/25/2025
The vulnerability identified as CVE-2008-4636 represents a critical privilege escalation flaw affecting yast2-backup versions 2.14.2 through 2.16.6 on SUSE and Novell Linux distributions. This issue stems from insufficient input validation within the backup process functionality, specifically when handling filenames that contain shell metacharacters. The flaw exists at the intersection of system administration tools and shell security practices, creating a pathway for local attackers to execute arbitrary commands with elevated privileges. The vulnerability is classified under CWE-78 as a failure to properly escape shell metacharacters, which directly enables command injection attacks. From an operational perspective, this vulnerability is particularly dangerous because it leverages the legitimate backup functionality of the system, making it difficult to detect through standard security monitoring. Attackers can exploit this by crafting malicious filenames containing shell operators such as semicolons, pipes, or command substitution characters that get executed during the backup process. The impact extends beyond simple privilege escalation to potentially allow full system compromise, as the executed commands run with the privileges of the backup process, which typically operates with elevated permissions. This vulnerability aligns with ATT&CK technique T1068, which covers local privilege escalation through the exploitation of system-level processes. The affected yast2-backup component is commonly used for system administration tasks, making it a prime target for attackers seeking persistent access to enterprise environments.
The technical exploitation of this vulnerability requires local access to the system and involves crafting filenames that contain shell metacharacters which are then processed by the backup utility. When the backup process encounters these specially crafted filenames, the shell metacharacters are interpreted and executed as commands, effectively bypassing normal access controls. The vulnerability demonstrates a classic command injection flaw where user-supplied input is directly concatenated into shell commands without proper sanitization or escaping. The affected system components include the yast2-backup package and related backup utilities that handle file naming conventions during backup operations. This vulnerability is particularly concerning in enterprise environments where system administrators frequently use backup tools for routine maintenance, as it can be exploited through seemingly benign backup operations. The exploitation process typically involves creating backup jobs with filenames containing malicious shell constructs, which are then processed by the backup daemon with elevated privileges. The vulnerability exists because the backup system does not properly validate or sanitize filenames before incorporating them into shell commands, creating an environment where attacker-controlled input can directly influence shell execution. This flaw is consistent with the broader category of injection vulnerabilities that affect system administration tools and configuration management utilities.
Mitigation strategies for CVE-2008-4636 require immediate patching of affected yast2-backup packages to versions that properly sanitize shell metacharacters in filenames. System administrators should implement strict input validation policies for all backup operations and consider disabling unnecessary backup features that process user-supplied filenames. The recommended approach includes upgrading to patched versions of SUSE and Novell Linux distributions where the vulnerability has been addressed through proper shell escaping mechanisms. Organizations should also implement monitoring for unusual backup activities and file naming patterns that might indicate exploitation attempts. Access controls should be strengthened to limit local user privileges and ensure that backup operations are performed with minimal necessary permissions. Network segmentation and privilege separation can help reduce the potential impact of successful exploitation by limiting lateral movement within the system. Security teams should conduct comprehensive vulnerability assessments to identify all systems running affected yast2-backup versions and prioritize remediation efforts based on risk exposure. The implementation of automated patch management processes can help prevent similar vulnerabilities from persisting in the environment. Regular security audits of system administration tools and backup processes should be conducted to identify potential injection points and ensure proper input validation mechanisms are in place. This vulnerability serves as a reminder of the critical importance of proper shell escaping and input validation in system administration tools, particularly those that operate with elevated privileges. The remediation process should include verification that all backup configurations properly handle special characters in filenames and that no user-controllable input is directly passed to shell execution contexts.