CVE-2020-14460 in Mattermost Server
Summary
by MITRE
An issue was discovered in Mattermost Server before 5.19.0, 5.18.1, 5.17.3, 5.16.5, and 5.9.8. Creation of a trusted OAuth application does not always require admin privileges, aka MMSA-2020-0001.
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Analysis
by VulDB Data Team • 10/26/2020
The vulnerability described in CVE-2020-14460 represents a critical authorization flaw within the Mattermost server authentication system that affects multiple version branches including 5.19.0, 5.18.1, 5.17.3, 5.16.5, and 5.9.8. This issue stems from improper privilege enforcement during the creation of trusted OAuth applications, creating a significant security risk that could allow unauthorized users to bypass administrative controls. The vulnerability is classified under CWE-284 which specifically addresses improper access control mechanisms, making it a direct violation of fundamental security principles that govern application privilege management. The flaw manifests when users with insufficient privileges can create trusted OAuth applications without requiring administrative approval or verification, effectively undermining the security model that should protect sensitive authentication configurations.
The technical implementation of this vulnerability occurs at the application level where the server fails to properly validate user permissions before allowing the creation of trusted OAuth applications. This oversight allows any authenticated user to potentially register OAuth applications that can be trusted by the system, which creates a pathway for malicious actors to establish unauthorized authentication endpoints. The flaw is particularly concerning because trusted OAuth applications can potentially bypass certain security checks and gain elevated privileges within the Mattermost environment. According to ATT&CK framework category T1548.003, this vulnerability enables privilege escalation through abuse of trusted application relationships, allowing attackers to establish persistent access points within the communication platform.
The operational impact of this vulnerability extends beyond simple privilege escalation as it creates potential for widespread security compromise within organizations using Mattermost platforms. An attacker who gains access to a user account could leverage this vulnerability to create trusted OAuth applications that could then be used to impersonate legitimate users or gain access to sensitive channels and data. The vulnerability affects the core authentication and authorization mechanisms of the platform, potentially allowing unauthorized access to private channels, user communications, and system configurations. Organizations relying on Mattermost for secure communications could face data leakage, unauthorized access to sensitive information, and potential lateral movement within their network infrastructure.
Organizations should immediately implement mitigations including upgrading to the patched versions of Mattermost server where version 5.19.0, 5.18.1, 5.17.3, 5.16.5, and 5.9.8 provide the necessary security fixes. Additionally, administrators should conduct thorough audits of existing OAuth applications to identify any unauthorized trusted applications that may have been created due to this vulnerability. The mitigation strategy should also include implementing strict access controls and monitoring for unauthorized OAuth application creation events. Security teams should also consider implementing network-level controls to monitor for suspicious OAuth-related activities and establish incident response procedures specifically addressing unauthorized trusted application creation. Regular security assessments should verify that proper privilege enforcement mechanisms are functioning correctly and that no unauthorized applications have been established within the Mattermost environment.