CVE-2018-11769 in CouchDB
Summary
by MITRE
CouchDB administrative users before 2.2.0 can configure the database server via HTTP(S). Due to insufficient validation of administrator-supplied configuration settings via the HTTP API, it is possible for a CouchDB administrator user to escalate their privileges to that of the operating system's user under which CouchDB runs, by bypassing the blacklist of configuration settings that are not allowed to be modified via the HTTP API. This privilege escalation effectively allows a CouchDB admin user to gain arbitrary remote code execution, bypassing CVE-2017-12636 and CVE-2018-8007.
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Analysis
by VulDB Data Team • 05/01/2023
The vulnerability identified as CVE-2018-11769 represents a critical privilege escalation flaw in Apache CouchDB versions prior to 2.2.0 that directly impacts the security posture of database administrators and system operators. This vulnerability operates within the context of CouchDB's HTTP(S) administration interface, where administrative users can configure database server settings through web-based APIs. The flaw stems from inadequate input validation mechanisms that fail to properly sanitize or verify configuration parameters submitted by administrative users, creating a pathway for malicious configuration modifications that can compromise the underlying operating system.
The technical implementation of this vulnerability involves a specific bypass of the built-in blacklist mechanism designed to prevent modification of critical system configuration parameters through the HTTP API. When administrative users attempt to modify certain configuration settings via the web interface, the system should reject any attempts to alter parameters that could compromise system integrity or escalate privileges. However, the insufficient validation allows attackers to circumvent these protections, enabling them to manipulate configuration settings that should remain restricted. This bypass effectively allows an authenticated CouchDB administrator to execute arbitrary code with the privileges of the operating system user running the CouchDB service, creating a direct path to full system compromise.
The operational impact of CVE-2018-11769 is severe and far-reaching, as it provides a direct route to remote code execution that bypasses other known security mitigations including CVE-2017-12636 and CVE-2018-8007. This vulnerability essentially neutralizes the security boundaries that should protect the database server from administrative privilege abuse, allowing a compromised administrator account to gain complete control over the underlying system. The implications extend beyond simple database compromise, as the attacker can now access system files, install malicious software, modify system configurations, and potentially escalate their access to other network resources. This vulnerability particularly affects environments where CouchDB is deployed with elevated privileges or where administrative accounts have been compromised through other attack vectors.
Security professionals should consider this vulnerability in the context of the MITRE ATT&CK framework, specifically under the privilege escalation and defense evasion tactics. The vulnerability aligns with CWE-20: Improper Input Validation, which represents a fundamental weakness in input sanitization that enables attackers to bypass security controls. Organizations should implement immediate mitigations including upgrading to CouchDB 2.2.0 or later versions that contain the necessary validation patches, implementing network segmentation to limit access to administrative interfaces, and employing strict access controls that reduce the attack surface for administrative accounts. Additionally, monitoring for suspicious configuration changes and implementing least-privilege principles for administrative access can help detect and prevent exploitation attempts. The vulnerability serves as a critical reminder of the importance of proper input validation and the potential consequences of inadequate security controls in administrative interfaces.