CVE-2024-39353 in Mattermost
Summary
by MITRE • 07/03/2024
Mattermost versions 9.5.x <= 9.5.5 and 9.8.0 fail to sanitize the RemoteClusterFrame payloads before audit logging them which allows a high privileged attacker with access to the audit logs to read message contents.
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Analysis
by VulDB Data Team • 07/06/2024
The vulnerability identified as CVE-2024-39353 affects Mattermost server versions 9.5.x through 9.5.5 and 9.8.0, representing a critical security flaw in the platform's audit logging mechanism. This issue stems from insufficient input validation and sanitization processes within the RemoteClusterFrame payload handling system, creating a significant information disclosure risk that directly impacts the confidentiality of communications within the Mattermost environment.
The technical flaw manifests when the Mattermost server processes RemoteClusterFrame payloads for audit logging purposes without properly sanitizing the data before storing it in audit logs. This sanitization failure allows malicious actors with elevated privileges to access sensitive message contents through the audit log system, effectively bypassing normal access controls and data protection mechanisms. The vulnerability specifically impacts the server's ability to properly filter and sanitize user-generated content before it enters the logging infrastructure, creating a direct pathway for information leakage.
From an operational perspective, this vulnerability represents a severe risk to organizations relying on Mattermost for secure communications, particularly those subject to compliance requirements such as gdpr, hipaa, or soc 2. The impact extends beyond simple information disclosure, as attackers with access to audit logs can reconstruct sensitive conversations, potentially exposing confidential business information, personal data, or proprietary communications. The high privilege requirement for exploitation means that the vulnerability is particularly dangerous when insider threats exist or when administrative credentials are compromised, as it allows for covert access to previously protected message content.
The vulnerability aligns with CWE-20, "Improper Input Validation," and CWE-22, "Improper Limitation of a Pathname to a Restricted Directory," as it demonstrates inadequate validation of incoming data and insufficient sanitization of audit log entries. From an attack framework perspective, this vulnerability maps to the ATT&CK technique T1567.002 "Exfiltration Over Web Service" and T1070.004 "Indicator Removal on Host" as it enables data exfiltration through legitimate audit logging channels while potentially masking the actual breach activity.
Organizations should immediately implement mitigations including updating to patched versions of Mattermost, implementing additional access controls for audit log systems, and establishing monitoring for unauthorized access to audit logs. The recommended remediation includes applying the vendor-provided security patches and ensuring that audit log access is strictly limited to authorized personnel with proper justification for such access. Additional defensive measures should include network segmentation of audit log systems, implementation of automated monitoring for suspicious audit log access patterns, and regular security assessments to identify potential unauthorized access to sensitive system components.