CVE-2017-14178 in systemd
Summary
by MITRE
In snapd 2.27 through 2.29.2 the 'snap logs' command could be made to call journalctl without match arguments and therefore allow unprivileged, unauthenticated users to bypass systemd-journald's access restrictions.
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Analysis
by VulDB Data Team • 02/03/2023
The vulnerability identified as CVE-2017-14178 represents a significant security flaw in the snapd package management system affecting versions 2.27 through 2.29.2. This issue stems from improper input validation within the snap logs command implementation, which creates an avenue for privilege escalation and unauthorized data access. The flaw specifically manifests when the snap logs command invokes journalctl without proper match arguments, effectively bypassing the access controls that systemd-journald normally enforces.
The technical implementation of this vulnerability occurs at the command execution layer where snapd fails to properly sanitize or validate the arguments passed to journalctl. When users execute the snap logs command, the system constructs a journalctl call that lacks specific match parameters, allowing the command to retrieve logs from the entire system journal rather than restricting access to logs associated with specific snaps or services. This design flaw enables any unprivileged user to access system logs that would normally be restricted to authorized administrators, fundamentally undermining the principle of least privilege that governs modern operating system security models.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with access to potentially sensitive system information that could be used for further exploitation. System logs often contain valuable data such as authentication attempts, service configurations, error messages, and other operational details that could reveal system architecture, running processes, and potential attack vectors. The vulnerability specifically targets the systemd-journald access controls, which are designed to prevent unauthorized access to system logs and maintain audit integrity across the system. This breach of access controls aligns with attack patterns described in the MITRE ATT&CK framework under the privilege escalation and credential access domains, where adversaries seek to bypass system protections to gain deeper insights into system operations.
From a compliance perspective, this vulnerability directly violates security standards established by organizations such as NIST and ISO 27001, which require proper access controls and audit trail protection. The flaw creates a situation where unauthenticated users can access system information that should remain restricted, potentially exposing the system to further compromise. The vulnerability also demonstrates poor input validation practices that align with CWE-20, which addresses "Improper Input Validation" in software security. This particular implementation flaw allows for command injection-like behavior through argument manipulation, where the lack of proper argument sanitization creates an unintended execution path that bypasses normal access control mechanisms.
Mitigation strategies for this vulnerability include immediate patching of affected snapd versions to 2.29.3 or later, where the issue has been resolved through proper argument validation. System administrators should also implement monitoring for unauthorized access attempts to system logs and ensure that proper access controls are in place for the snapd service itself. Additionally, organizations should consider implementing network segmentation and access controls that limit exposure to systems running affected versions of snapd, while also conducting regular security assessments to identify similar input validation vulnerabilities in other system components. The fix typically involves ensuring that the snap logs command properly validates and sanitizes arguments before passing them to journalctl, thereby preventing the bypass of systemd-journald's access restrictions.