CVE-2016-8746 in Ranger
Summary
by MITRE
Apache Ranger before 0.6.3 policy engine incorrectly matches paths in certain conditions when policy does not contain wildcards and has recursion flag set to true.
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Analysis
by VulDB Data Team • 12/28/2020
The vulnerability identified as CVE-2016-8746 affects Apache Ranger versions prior to 0.6.3 and represents a critical flaw in the policy engine's path matching algorithm. This issue specifically manifests when policies are configured without wildcards but with the recursion flag explicitly set to true, creating a dangerous condition where access controls can be bypassed through improper path resolution. The flaw stems from how Ranger processes directory traversal scenarios where recursive matching is enabled, leading to potential unauthorized access to resources that should be restricted by policy controls.
The technical implementation of this vulnerability resides in the path matching logic within Apache Ranger's policy engine component. When a policy contains a path specification with recursion enabled but no wildcard characters, the system fails to properly validate the boundary conditions of directory traversal. This misconfiguration allows attackers to craft requests that match against policy rules in unexpected ways, effectively bypassing the intended access controls. The issue is particularly concerning because it operates at the core policy enforcement layer, where proper access control decisions are made, and can be exploited to gain unauthorized access to sensitive data or system resources. The flaw demonstrates a classic path traversal vulnerability pattern that can be categorized under CWE-22, which specifically addresses improper limitation of a pathname to a restricted directory.
The operational impact of this vulnerability extends beyond simple access control bypasses, as it can enable attackers to escalate privileges and gain access to resources they should not be permitted to access. In environments where Apache Ranger is used for data protection and access control management, this flaw could allow unauthorized users to traverse directories and access sensitive information stored in nested folder structures. The vulnerability is particularly dangerous in data governance scenarios where strict access controls are required to protect confidential data, as it undermines the fundamental security model that Ranger is designed to enforce. Attackers could leverage this weakness to access files, directories, or data sets that are protected by policies that explicitly restrict access to specific users or groups.
Mitigation strategies for CVE-2016-8746 should prioritize immediate upgrades to Apache Ranger version 0.6.3 or later, which contains the necessary fixes for the path matching algorithm. Organizations should also conduct comprehensive audits of their existing Ranger policies to identify configurations that utilize recursive matching without wildcards, as these are particularly vulnerable to exploitation. Security teams should implement additional monitoring and logging around access control decisions to detect potential exploitation attempts. The remediation process should include thorough testing of policy configurations to ensure that recursive path matching behaves as expected and that no unintended access paths are created. Additionally, organizations should consider implementing principle of least privilege configurations and regularly review access control policies to minimize the impact of any potential exploitation attempts. This vulnerability highlights the importance of proper input validation and boundary checking in security-critical systems and aligns with ATT&CK technique T1078 for valid accounts and T1566 for credential access through privilege escalation scenarios.