CVE-2023-3584 in Server
Summary
by MITRE • 07/17/2023
Mattermost fails to properly check the authorization of POST /api/v4/teams when passing a team override scheme ID in the request, allowing an authenticated attacker with knowledge of a Team Override Scheme ID to create a new team with said team override scheme.
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Analysis
by VulDB Data Team • 07/17/2023
The vulnerability identified as CVE-2023-3584 affects the Mattermost collaborative platform, specifically targeting the authorization mechanisms within the team creation endpoint. This issue stems from inadequate validation of access controls when processing requests to the POST /api/v4/teams API endpoint. The flaw allows authenticated attackers who possess knowledge of a specific Team Override Scheme ID to bypass normal authorization checks and create new teams using that scheme. The vulnerability represents a significant authorization bypass that could enable attackers to manipulate team structures and potentially gain elevated privileges within the platform's organizational hierarchy.
The technical implementation of this vulnerability resides in the server-side validation logic that governs team creation operations. When a request is made to the /api/v4/teams endpoint with a team override scheme ID parameter, the system should verify that the authenticated user has appropriate permissions to utilize that specific scheme. However, the current implementation fails to properly validate whether the requesting user possesses the necessary authorization levels to employ the specified team override scheme. This validation gap occurs at the application layer where access control decisions are made, specifically within the API endpoint handler for team creation. The flaw essentially allows any authenticated user who can discover a valid Team Override Scheme ID to create teams with potentially elevated permissions or specific configurations that should be restricted to authorized administrators.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it enables attackers to manipulate the fundamental organizational structure of Mattermost instances. An attacker could create new teams with specific override schemes that might grant them access to restricted channels, modify team permissions, or establish team hierarchies that bypass normal administrative controls. This capability could lead to data exposure, unauthorized access to sensitive communications, and potential lateral movement within the platform's security boundaries. The vulnerability particularly affects organizations that rely on Mattermost for secure collaboration and require strict control over team creation and permission management. From a cybersecurity perspective, this issue aligns with CWE-285, which addresses improper authorization in software systems, and represents a clear violation of the principle of least privilege.
Organizations using Mattermost should implement immediate mitigations to address this vulnerability, including updating to the latest version where the authorization checks have been properly implemented. Network segmentation and monitoring of API endpoint access patterns can help detect anomalous team creation activities that might indicate exploitation attempts. The implementation of additional access controls and audit logging around team creation operations provides defense in depth. Security teams should also review existing team override scheme configurations to ensure that sensitive schemes are not easily discoverable through enumeration or other reconnaissance techniques. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and persistence within the application environment. The vulnerability demonstrates how insufficient authorization checks can create opportunities for attackers to establish footholds within collaborative platforms, potentially leading to more severe compromise scenarios involving data exfiltration or insider threat exploitation.