CVE-2021-3642 in Elytron
Summary
by MITRE • 08/06/2021
A flaw was found in Wildfly Elytron where ScramServer may be susceptible to Timing Attack if enabled. The highest threat of this vulnerability is confidentiality. This flaw affectes Wildfly Elytron versions prior to 1.10.14.Final, prior to 1.15.5.Final and prior to 1.16.1.Final.
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Analysis
by VulDB Data Team • 08/10/2021
The vulnerability identified as CVE-2021-3642 resides within Wildfly Elytron's SCRAM (Salted Challenge Response Authentication Mechanism) server implementation, presenting a significant confidentiality risk through timing attack susceptibility. This flaw specifically impacts the authentication process where the system's response time may inadvertently reveal information about the authentication attempt, creating a window for attackers to exploit temporal variations in processing. The vulnerability affects multiple version streams of Wildfly Elytron, with specific remediation targets including versions 1.10.14.Final, 1.15.5.Final, and 1.16.1.Final, indicating a widespread exposure across the product's release lifecycle.
The technical nature of this vulnerability stems from the implementation of the ScramServer component which handles authentication challenges and responses in a manner that does not provide constant-time execution for critical cryptographic operations. When processing authentication requests, the system's timing behavior varies depending on whether the provided credentials match the expected values, creating measurable differences in response times that can be exploited by attackers. This timing variation occurs during the validation of authentication tokens or password verifications where the system's processing time is directly influenced by the correctness of input data, thereby leaking information about the authentication state through temporal side channels.
The operational impact of this vulnerability extends beyond simple credential theft, as it represents a sophisticated attack vector that can be leveraged to perform credential brute force attacks with significantly reduced effort. Attackers can exploit the timing discrepancies to determine whether specific username-password combinations are valid, effectively bypassing traditional authentication protections and potentially leading to full system compromise. The confidentiality threat level is elevated because the vulnerability does not require direct access to encrypted communications or system resources, but rather relies on monitoring response times to infer authentication success or failure. This makes the attack surface particularly concerning as it can be executed remotely and systematically without requiring physical access or complex infrastructure.
Security practitioners should prioritize immediate remediation by upgrading to the affected version releases mentioned in the advisory, specifically targeting the patch levels 1.10.14.Final, 1.15.5.Final, and 1.16.1.Final to ensure proper constant-time implementation of authentication routines. Additional mitigations include implementing rate limiting mechanisms to prevent rapid successive authentication attempts, deploying intrusion detection systems that can monitor for unusual timing patterns, and considering the use of hardware security modules that provide constant-time cryptographic operations. Organizations should also conduct thorough security assessments of their authentication infrastructure to identify other potential timing vulnerabilities in related components. This vulnerability aligns with CWE-203, which specifically addresses "Observable Timing Discrepancy" and represents a classic example of how seemingly innocuous implementation details can create significant security weaknesses. The attack pattern follows ATT&CK technique T1110.003, which covers credential guessing through timing attacks, making this vulnerability particularly relevant for organizations implementing robust authentication frameworks that must defend against sophisticated adversarial approaches.