CVE-2020-27508 in Frappe
Summary
by MITRE • 12/11/2020
In two-factor authentication, the system also sending 2fa secret key in response, which enables an intruder to breach the 2fa security.
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Analysis
by VulDB Data Team • 12/16/2020
The vulnerability described in CVE-2020-27508 represents a critical flaw in two-factor authentication systems where the secret key used for generating time-based one-time passwords is inadvertently transmitted alongside the authentication response. This represents a fundamental security failure that directly undermines the core principle of multi-factor authentication. The flaw falls under CWE-312, which specifically addresses the exposure of sensitive information through improper handling of authentication tokens. When an attacker can intercept or access this secret key, they effectively bypass the entire two-factor authentication mechanism, as they can generate valid authentication codes without possessing the physical device or having access to the user's possession factor.
The technical implementation of this vulnerability typically occurs in systems that fail to properly separate authentication responses from secret key distribution. In many cases, the system generates a secret key for each user and stores it in a database or configuration file, but during the authentication process, this key is included in the response payload to the client or server. This creates a scenario where an attacker who gains access to the authentication response can extract the secret key and use it to generate valid authentication tokens. The flaw is particularly dangerous because it affects the underlying cryptographic foundation of the authentication system, making it susceptible to replay attacks and unauthorized access attempts.
The operational impact of CVE-2020-27508 extends far beyond simple unauthorized access, as it fundamentally compromises the security posture of any system relying on two-factor authentication. According to ATT&CK framework, this vulnerability maps to T1566, which covers credential access through social engineering, and T1078, which addresses valid accounts usage. Attackers can leverage this weakness to escalate privileges, move laterally within networks, and potentially gain access to sensitive data or systems that would normally be protected by strong authentication controls. The vulnerability is particularly concerning in environments where two-factor authentication is implemented as a primary security control, as it essentially renders that control ineffective. Organizations using affected systems may experience unauthorized access to user accounts, potential data breaches, and compromise of sensitive information that was supposed to be protected by multi-factor authentication.
Mitigation strategies for this vulnerability should focus on implementing proper separation of authentication responses from secret key distribution. Organizations must ensure that secret keys are never transmitted in authentication responses, and that proper access controls are implemented to prevent unauthorized access to these keys. The solution involves implementing secure key management practices, including storing secret keys in secure hardware modules or encrypted storage, and ensuring that authentication responses contain only the necessary information for verification without exposing underlying cryptographic materials. Additionally, organizations should implement monitoring for anomalous authentication patterns and establish procedures for key rotation and secure key distribution. The remediation process should include comprehensive code reviews to identify all instances where secret keys might be inadvertently exposed, and implementation of proper cryptographic key management protocols to ensure that the integrity and confidentiality of authentication secrets are maintained throughout the authentication lifecycle.