CVE-2018-21249 in Mattermost Server
Summary
by MITRE
An issue was discovered in Mattermost Server before 5.3.0. It mishandles timing.
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Analysis
by VulDB Data Team • 10/25/2020
The vulnerability identified as CVE-2018-21249 represents a timing-related issue within the Mattermost Server software ecosystem prior to version 5.3.0. This flaw falls under the broader category of timing attack vulnerabilities that exploit the time taken by cryptographic operations or system responses to infer sensitive information. The issue manifests in how the server processes and handles timing characteristics during authentication and authorization procedures, creating potential avenues for attackers to gain unauthorized access or extract confidential data through temporal analysis.
The technical implementation of this vulnerability stems from inconsistent timing behavior in the server's response mechanisms. When users attempt authentication or perform sensitive operations, the server's response times vary based on whether certain validation checks pass or fail. This timing variance creates observable patterns that can be exploited by attackers to determine the validity of usernames, passwords, or other authentication credentials through statistical analysis of response delays. The flaw specifically affects the server's handling of authentication challenges and may expose information about account existence or password correctness through timing discrepancies.
From an operational perspective, this vulnerability presents significant risks to organizations relying on Mattermost Server for secure communication and collaboration. Attackers could potentially perform credential stuffing attacks or brute force attempts with reduced computational overhead by leveraging timing information to eliminate invalid candidates more efficiently. The impact extends beyond simple authentication bypasses to include potential account enumeration and privilege escalation scenarios, particularly when combined with other attack vectors. Security teams must recognize that this timing issue could enable attackers to systematically identify valid user accounts and subsequently target them with more sophisticated attacks.
The vulnerability aligns with CWE-347, which addresses improper certificate validation and authentication mechanisms that can be exploited through timing variations. It also maps to ATT&CK technique T1110.003, which covers credential guessing through timing-based analysis. Organizations should implement immediate mitigations including updating to Mattermost Server version 5.3.0 or later, which addresses the timing inconsistencies in authentication handling. Additional protective measures include implementing constant-time comparison algorithms for credential validation, adding rate limiting mechanisms, and deploying monitoring systems to detect unusual timing patterns that may indicate exploitation attempts. Network-level protections such as intrusion detection systems can help identify potential timing attack patterns while application-level controls should focus on eliminating timing variations in authentication responses to prevent information leakage through temporal side channels.