CVE-2021-25643 in Server
Summary
by MITRE • 05/27/2021
An issue was discovered in Couchbase Server 5.x and 6.x before 6.5.2 and 6.6.x before 6.6.2. Internal users with administrator privileges, @cbq-engine-cbauth and @index-cbauth, leak credentials in cleartext in the indexer.log file when they make a /listCreateTokens, /listRebalanceTokens, or /listMetadataTokens call.
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Analysis
by VulDB Data Team • 05/30/2021
The vulnerability identified as CVE-2021-25643 represents a critical credential leakage issue within Couchbase Server versions 5.x and 6.x prior to specific patch releases. This flaw affects the database management system's logging mechanisms and exposes sensitive authentication information to unauthorized parties within the system. The vulnerability specifically impacts internal user accounts designated with administrator privileges, namely cbq-engine-cbauth and index-cbauth, which are essential components of Couchbase's query engine and indexing services respectively.
The technical implementation of this vulnerability stems from improper handling of authentication tokens within the indexer logging subsystem. When these privileged internal accounts execute specific API calls including /listCreateTokens, /listRebalanceTokens, or /listMetadataTokens, the system inadvertently logs cleartext credentials to the indexer.log file. This occurs because the logging mechanism fails to properly sanitize or obfuscate sensitive authentication data during these operations. The flaw essentially creates a persistent exposure point where administrative credentials become accessible through standard log file analysis, bypassing normal access controls and authentication mechanisms that would typically protect such sensitive information.
The operational impact of this vulnerability extends beyond simple credential exposure, as it provides attackers with elevated privileges within the database environment. The leaked credentials can be exploited to gain unauthorized access to database resources, potentially leading to data exfiltration, manipulation, or complete system compromise. Since these are internal administrative accounts with broad privileges, the credential leakage could enable attackers to perform operations such as creating new users, modifying database configurations, accessing sensitive data, or even executing arbitrary code within the Couchbase environment. The cleartext nature of the leaked credentials makes exploitation particularly straightforward, as no additional cryptographic challenges are present for attackers attempting to leverage the exposed information.
Security professionals should note that this vulnerability aligns with CWE-209, which addresses "Information Exposure Through an Error Message," and more specifically with CWE-312, "Cleartext Storage of Sensitive Information." The issue also maps to ATT&CK technique T1566, "Phishing," as attackers could potentially leverage these exposed credentials to gain initial access, and T1078, "Valid Accounts," since the compromised credentials represent legitimate administrative access. Organizations should immediately implement patches for Couchbase Server versions 6.5.2 and 6.6.2 to address this vulnerability, while also conducting thorough log analysis to identify any potential exploitation attempts. Additionally, implementing proper log monitoring and access controls for sensitive log files, along with regular credential rotation practices, would significantly reduce the risk associated with this exposure. The vulnerability demonstrates the critical importance of proper input sanitization and output handling within database management systems, particularly when dealing with administrative functions that require elevated privileges.