CVE-2020-16272 in KeePassRPC
Summary
by MITRE
The SRP-6a implementation in Kee Vault KeePassRPC before 1.12.0 is missing validation for a client-provided parameter, which allows remote attackers to read and modify data in the KeePass database via an A=0 WebSocket connection.
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Analysis
by VulDB Data Team • 08/04/2020
The vulnerability identified as CVE-2020-16272 resides within the SRP-6a secure remote password protocol implementation in Kee Vault KeePassRPC versions prior to 1.12.0. This represents a critical security flaw that undermines the cryptographic integrity of the authentication mechanism designed to protect KeePass database access. The issue stems from insufficient validation of client-provided parameters during the SRP-6a key exchange process, creating a pathway for remote attackers to exploit the system. The vulnerability specifically manifests when an attacker can manipulate the A parameter in the SRP-6a protocol to a value of zero, effectively bypassing the normal authentication sequence.
The technical flaw exploits a fundamental weakness in the SRP-6a implementation where the system fails to validate that the client-provided parameter A is within acceptable cryptographic bounds. In standard SRP-6a implementations, parameter A should be a valid element of the cryptographic group being used, typically requiring A to be between 1 and N-1 where N is the prime modulus. When A=0 is accepted without validation, it creates a mathematical weakness that allows attackers to compute the shared secret without proper authentication. This particular vulnerability enables attackers to establish a WebSocket connection with the KeePassRPC service and manipulate the SRP-6a protocol flow, ultimately gaining unauthorized access to the protected database content.
The operational impact of this vulnerability extends far beyond simple authentication bypass. Attackers who successfully exploit this weakness can read and modify sensitive data stored within the KeePass database, potentially accessing passwords, personal information, and other confidential entries that the database is designed to protect. The remote nature of the attack means that an attacker does not require physical access to the system or network, making this vulnerability particularly dangerous in environments where KeePassRPC is exposed to untrusted networks. The WebSocket connection aspect of the attack vector suggests that this vulnerability could be exploited through web-based interfaces or applications that utilize the KeePassRPC service, expanding the potential attack surface significantly.
This vulnerability aligns with CWE-310, which addresses cryptographic weaknesses in authentication protocols, and specifically relates to improper validation of cryptographic parameters. The attack pattern follows techniques described in the MITRE ATT&CK framework under T1566 for credential access through network attacks. Organizations using KeePassRPC implementations prior to version 1.12.0 face significant risk of data compromise, as the vulnerability allows for both data exfiltration and modification of stored credentials. The flaw represents a failure in proper cryptographic protocol implementation where basic parameter validation was omitted, creating a critical security gap that undermines the entire authentication framework. The vulnerability demonstrates the importance of rigorous cryptographic implementation review and adherence to established security standards, as even minor oversights in parameter validation can result in complete system compromise.
Mitigation strategies should focus on immediate upgrade to KeePassRPC version 1.12.0 or later, which contains the necessary parameter validation fixes. Organizations should also implement network segmentation to limit access to KeePassRPC services, deploy intrusion detection systems to monitor for unusual WebSocket connections, and conduct thorough security assessments of all cryptographic implementations. Additional defensive measures include monitoring for unauthorized access attempts, implementing multi-factor authentication where possible, and regularly auditing database access logs for suspicious activities. The vulnerability serves as a reminder of the critical importance of proper cryptographic implementation and the necessity of thorough security testing, particularly for authentication mechanisms that handle sensitive credential data.