CVE-2018-14348 in libcgroup
Summary
by MITRE
libcgroup up to and including 0.41 creates /var/log/cgred with mode 0666 regardless of the configured umask, leading to disclosure of information.
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Analysis
by VulDB Data Team • 05/02/2023
The vulnerability identified as CVE-2018-14348 affects the libcgroup library version 0.41 and earlier, specifically targeting the improper handling of file permissions during log file creation. This issue manifests when the cgred daemon initializes and creates the /var/log/cgred log file with world-writable permissions set to 0666, completely ignoring the system's configured umask setting. The fundamental flaw lies in the library's failure to respect standard Unix permission conventions and system security configurations that typically rely on umask values to control default file creation permissions. This behavior represents a significant deviation from expected security practices and creates an exploitable condition that compromises system integrity.
The technical implementation of this vulnerability stems from the libcgroup library's hardcoded permission settings during the log file creation process. When the cgred service starts and attempts to write logs to /var/log/cgred, it explicitly sets the file permissions to 0666 regardless of the umask value configured on the system. This approach directly violates the principle of least privilege and standard security practices that rely on umask values to establish appropriate default permissions for newly created files. The issue is particularly concerning because it affects a system component that handles group management and resource control, making it a potential vector for information disclosure attacks. From a cybersecurity perspective, this vulnerability maps to CWE-732: Incorrect Permission Assignment for Critical Resource, which specifically addresses the creation of files with overly permissive access controls.
The operational impact of this vulnerability extends beyond simple information disclosure, as it creates persistent security weaknesses that can be exploited by local attackers with minimal privileges. An attacker with access to a system running vulnerable libcgroup versions can potentially read sensitive information contained within the cgred log files, including process details, resource allocations, and group management activities that may reveal system configuration information or operational patterns. The persistent nature of this vulnerability means that the world-writable log file remains accessible to all users on the system, creating a continuous risk window. This issue is particularly dangerous in multi-user environments or shared hosting scenarios where unauthorized users might gain access to sensitive system information. The vulnerability also aligns with ATT&CK technique T1083: File and Directory Discovery, as it creates easily accessible log files that could be used for reconnaissance purposes. Additionally, the flaw contributes to broader system compromise potential by providing attackers with additional information that could be leveraged in subsequent attack phases.
Mitigation strategies for CVE-2018-14348 should focus on immediate patching of affected systems with updated libcgroup versions that properly respect umask values during log file creation. System administrators should also implement monitoring for unauthorized access to the /var/log/cgred file and consider implementing file integrity monitoring solutions to detect any unauthorized modifications to log files. The recommended approach includes updating the libcgroup package to version 0.42 or later, which addresses the improper permission handling issue. Organizations should also review their system configurations to ensure that umask values are properly set to restrictive defaults, typically 022 or 077, to minimize the impact of similar issues. Security teams should conduct comprehensive audits of all system components that handle log file creation to identify potential similar vulnerabilities, as this represents a pattern of improper permission handling that could affect other system services. The remediation process should include verifying that log files are created with appropriate permissions that respect system security policies rather than hardcoded values that override system configurations.