CVE-2024-9155 in Mattermost
Summary
by MITRE • 09/26/2024
Mattermost versions 9.10.x <= 9.10.1, 9.9.x <= 9.9.2, 9.5.x <= 9.5.8 fail to limit access to channels files that have not been linked to a post which allows an attacker to view them in channels that they are a member of.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 10/19/2024
The vulnerability described in CVE-2024-9155 represents a critical access control flaw within the Mattermost collaboration platform that affects multiple version streams including 9.10.x up to 9.10.1, 9.9.x up to 9.9.2, and 9.5.x up to 9.5.8. This issue stems from inadequate authorization mechanisms that permit unauthorized access to channel files that exist outside of post contexts, creating a significant security risk for organizations relying on Mattermost for secure communication and file sharing.
The technical nature of this vulnerability involves a failure in the platform's file access control system where files uploaded to channels but not explicitly linked to posts can be accessed by any member of that channel regardless of their intended access permissions. This represents a direct violation of the principle of least privilege and demonstrates a fundamental flaw in how the system handles file visibility and access control. The vulnerability allows attackers to bypass normal file sharing restrictions and access content that should remain restricted to specific users or groups.
From an operational perspective, this vulnerability poses substantial risks to organizations using Mattermost for sensitive communications and document sharing. Attackers who gain membership to a channel can potentially access confidential files, proprietary information, or sensitive data that was intended to be restricted to specific individuals or teams. The impact extends beyond simple information disclosure as it undermines the entire security model of the platform, potentially exposing intellectual property, personal data, or other sensitive materials that should remain protected within the confines of proper access controls.
This vulnerability aligns with CWE-284 which addresses improper access control issues in software systems, specifically targeting inadequate authorization mechanisms that allow unauthorized access to resources. The flaw also relates to ATT&CK technique T1078 which covers legitimate credentials usage, as attackers can leverage their membership in channels to access files they should not have permission to view. Organizations should implement immediate mitigations including updating to patched versions of Mattermost, reviewing channel membership and file sharing settings, and conducting comprehensive security audits of file access controls within their collaboration environments. The vulnerability underscores the critical importance of proper access control implementation in enterprise communication platforms where unauthorized file access can have severe implications for data integrity and organizational security.
The security implications of this flaw extend to potential compliance violations under data protection regulations such as gdpr and hipaa, where unauthorized access to sensitive files could result in significant regulatory penalties and legal consequences. Organizations must also consider the broader impact on their security posture, as this vulnerability could serve as a foothold for more sophisticated attacks or provide attackers with information that could be used to compromise other systems within their network infrastructure.