CVE-2023-4108 in Mattermost
Summary
by MITRE • 08/11/2023
Mattermost fails to sanitize post metadata during audit logging resulting in permalinks contents being logged
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Analysis
by VulDB Data Team • 09/08/2023
The vulnerability identified as CVE-2023-4108 affects the Mattermost collaboration platform, specifically exposing a critical flaw in how the system handles audit logging of post metadata. This issue arises when the platform fails to properly sanitize or filter content that gets recorded in audit logs, creating a potential security risk that could compromise user privacy and data integrity. The flaw is particularly concerning because it directly impacts the logging mechanisms that organizations rely on for compliance monitoring, security auditing, and incident response activities.
The technical implementation of this vulnerability stems from inadequate input validation and sanitization processes within Mattermost's audit logging subsystem. When users create posts containing specific metadata elements, the system erroneously includes these unfiltered elements in audit log entries without proper sanitization procedures. This oversight allows potentially sensitive information embedded within permalink structures and other metadata fields to be captured and stored in plain text within audit logs. The vulnerability specifically manifests when the platform processes post creation events and generates corresponding audit records, where the sanitization logic fails to properly strip or encode metadata components that might contain confidential data.
From an operational perspective, this vulnerability creates significant risks for organizations using Mattermost in regulated environments or those subject to compliance requirements such as gdpr, hipaa, or soc 2 standards. The exposure of permalink contents in audit logs could potentially reveal sensitive information about user activities, internal communications, or system configurations that should remain private. Security teams relying on audit logs for threat detection and forensic analysis may inadvertently gain access to information that was never intended for public viewing within their logging infrastructure. The impact extends beyond simple privacy concerns to potentially enable advanced persistent threat actors to gather intelligence about system usage patterns and user behaviors through careful analysis of the compromised audit records.
Organizations should implement immediate mitigations including configuring audit log filtering to exclude metadata fields that contain sensitive permalink information, deploying additional log sanitization measures, and conducting comprehensive audits of existing audit log content to identify any previously exposed sensitive data. The vulnerability aligns with CWE-20, which addresses improper input validation, and represents a specific instance of CWE-117, concerning inadequate output escaping or encoding in security contexts. From an attack surface perspective, this flaw maps to multiple ATT&CK techniques including TA0007 (Discovery) where adversaries might gather system information through log analysis, and TA0006 (Credential Access) if the exposed metadata contains information that could aid in credential compromise or privilege escalation. Organizations should also consider implementing log rotation policies with enhanced sanitization routines and establish monitoring procedures to detect unusual patterns in audit log content that might indicate further exploitation attempts.