CVE-2019-20875 in Mattermost Server
Summary
by MITRE
An issue was discovered in Mattermost Server before 5.9.0, 5.8.1, 5.7.3, and 4.10.8. It allows a password reset to proceed while an e-mail address is being changed.
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Analysis
by VulDB Data Team • 10/25/2020
This vulnerability exists in Mattermost Server versions prior to 5.9.0, 5.8.1, 5.7.3, and 4.10.8, representing a critical security flaw that undermines the integrity of user account management processes. The issue manifests when a user attempts to reset their password while simultaneously requesting an email address change, creating a dangerous race condition in the authentication system. This flaw falls under CWE-284, which addresses improper access control, and specifically relates to inadequate privilege management during credential operations. The vulnerability enables malicious actors to exploit the temporal gap between email verification and password reset procedures, potentially allowing unauthorized access to user accounts.
The technical implementation of this flaw occurs within the server's session management and authentication flow where the system fails to properly validate that the email address associated with a password reset request matches the one currently registered for the user account. When a user initiates both actions concurrently, the system processes the password reset without verifying that the email address being reset has not been modified to a different address. This creates a window where an attacker could intercept the password reset email sent to a compromised address and gain access to the account. The flaw is particularly dangerous because it bypasses standard email verification mechanisms that should prevent unauthorized password resets.
The operational impact of this vulnerability extends beyond simple account compromise, as it enables a range of malicious activities that align with ATT&CK technique T1078 for valid accounts and T1531 for account access. Attackers could leverage this vulnerability to perform account takeover operations, access sensitive communications, manipulate team settings, and potentially escalate privileges within the Mattermost environment. The vulnerability affects organizations that rely on Mattermost for secure communications, as it undermines the fundamental security assumptions of password reset procedures and email-based authentication. Organizations using older versions of Mattermost may experience unauthorized access to confidential discussions, file sharing activities, and collaborative workspaces.
Mitigation strategies should include immediate deployment of patched Mattermost server versions, implementation of additional email verification checks, and enhanced monitoring of password reset activities. Organizations should also consider implementing multi-factor authentication as an additional security layer and establish logging procedures to detect suspicious concurrent account modification attempts. The fix addresses the root cause by ensuring that password reset operations require verification of the current email address before proceeding, preventing the race condition that enabled this attack vector. Security teams should also conduct comprehensive audits of their Mattermost implementations to identify any other potential vulnerabilities in authentication workflows that might be susceptible to similar temporal race condition attacks.