CVE-2016-6651 in Cloud Foundry
Summary
by MITRE
The UAA /oauth/token endpoint in Pivotal Cloud Foundry (PCF) before 243; UAA 2.x before 2.7.4.8, 3.x before 3.3.0.6, and 3.4.x before 3.4.5; UAA BOSH before 11.7 and 12.x before 12.6; Elastic Runtime before 1.6.40, 1.7.x before 1.7.21, and 1.8.x before 1.8.2; and Ops Manager 1.7.x before 1.7.13 and 1.8.x before 1.8.1 allows remote authenticated users to gain privileges by leveraging possession of a token.
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Analysis
by VulDB Data Team • 04/28/2019
The vulnerability described in CVE-2016-6651 represents a critical privilege escalation flaw within the User Account and Authentication (UAA) service of Pivotal Cloud Foundry platforms. This issue affects multiple versions of the UAA component across different PCF releases, including UAA 2.x versions prior to 2.7.4.8, UAA 3.x versions before 3.3.0.6, and UAA 3.4.x versions before 3.4.5, along with corresponding BOSH releases and Elastic Runtime versions. The vulnerability specifically targets the /oauth/token endpoint, which serves as a fundamental authentication mechanism for the platform's security infrastructure.
The technical flaw stems from improper token validation and authorization checks within the UAA service's token endpoint implementation. When authenticated users possess valid tokens, the system fails to adequately verify the scope and permissions associated with those tokens before granting access to sensitive operations. This weakness allows malicious actors who have obtained legitimate tokens to exploit the system's trust model and escalate their privileges beyond what their original token authorization should permit. The vulnerability operates under the Common Weakness Enumeration classification of CWE-269, which deals with improper privileges, specifically focusing on insufficient authorization checks in authentication systems.
From an operational impact perspective, this vulnerability creates a significant security risk for organizations deploying Pivotal Cloud Foundry environments. Attackers who gain access to any valid authentication token can leverage this flaw to perform unauthorized privilege escalation attacks, potentially gaining administrative access to the platform's user management and authorization systems. This could enable unauthorized users to create new accounts, modify existing user permissions, access sensitive application data, or manipulate the underlying infrastructure. The vulnerability's impact extends across the entire PCF ecosystem, affecting not just individual applications but the foundational security controls that protect the platform's integrity.
Organizations should implement immediate mitigations including upgrading to the patched versions of UAA components mentioned in the CVE description, specifically versions 2.7.4.8, 3.3.0.6, and 3.4.5 respectively. Additionally, security teams should conduct comprehensive token lifecycle management reviews, implement stricter token scope validation, and establish monitoring for unusual privilege escalation patterns. The mitigation strategy should align with ATT&CK framework techniques related to privilege escalation and credential access, particularly focusing on T1078 for valid accounts and T1550 for use of stolen credentials. Organizations should also consider implementing additional security controls such as token binding, enhanced session management, and regular security audits of authentication flows to prevent exploitation of similar vulnerabilities in the future.