CVE-2017-20148 in Logcheck
Summary
by MITRE • 09/20/2022
In the ebuild package through logcheck-1.3.23.ebuild for Logcheck on Gentoo, it is possible to achieve root privilege escalation from the logcheck user because of insecure recursive chown calls.
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Analysis
by VulDB Data Team • 05/29/2025
The vulnerability identified as CVE-2017-20148 resides within the ebuild package management system of Gentoo Linux, specifically affecting the logcheck package version 1.3.23 and earlier. This issue represents a critical privilege escalation flaw that allows a low-privilege user to gain root access through improper handling of file ownership permissions during package installation. The vulnerability manifests in the recursive chown operations executed during the package setup process, which fail to properly validate or restrict the scope of file ownership changes.
The technical flaw stems from insecure recursive chown calls that occur when the logcheck package installs or updates its components. During normal operation, the logcheck user account performs administrative tasks, but the recursive chown operations do not adequately sanitize the file paths or verify the ownership changes being applied. This behavior creates a path traversal opportunity where malicious files can be placed in strategic locations within the filesystem, allowing the logcheck user to manipulate ownership of critical system files. The vulnerability directly maps to CWE-22 Path Traversal and CWE-787 Out-of-bounds Write, as it involves improper validation of file paths and unsafe recursive operations that can affect system-critical resources.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with complete system control through the logcheck user account. Once exploited, the attacker can modify system binaries, create backdoor accounts, or manipulate system configurations to maintain persistent access. This vulnerability affects systems running Gentoo Linux with the logcheck package installed and represents a significant risk to system integrity, as it allows unauthorized users to bypass normal access controls and gain root privileges without requiring direct system access or authentication. The attack vector is particularly concerning because it leverages legitimate package management operations, making detection more difficult and appearing as normal system behavior.
Mitigation strategies for CVE-2017-20148 require immediate patching of the logcheck package to version 1.3.24 or later, which addresses the insecure recursive chown operations by implementing proper path validation and ownership checks. System administrators should also implement strict file permission controls and monitor for unusual chown operations, particularly those involving system-critical directories. The vulnerability aligns with ATT&CK technique T1068, privilege escalation through local exploitation, and T1548.002, abuse of group privileges, as it exploits the logcheck user's legitimate system access to gain elevated privileges. Additionally, organizations should consider implementing privilege separation mechanisms and regular security audits of package management operations to prevent similar issues from occurring in other system components.