CVE-2016-2016 in Base-VxFS
Summary
by MITRE
Base-VxFS-50 B.05.00.01 through B.05.00.02, Base-VxFS-501 B.05.01.0 through B.05.01.03, and Base-VxFS-51 B.05.10.00 through B.05.10.02 on HPE HP-UX 11iv3 with VxFS 5.0, VxFS 5.0.1, and VxFS 5.1SP1 mishandles ACL inheritance for default:class: entries, default:other: entries, and default:user: entries, which allows local users to bypass intended access restrictions by leveraging the configuration of a parent directory.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 10/11/2024
This vulnerability resides in the Veritas File System (VxFS) implementation on HPE HP-UX 11iv3 systems, specifically affecting versions ranging from B.05.00.01 through B.05.00.02, B.05.01.0 through B.05.01.03, and B.05.10.00 through B.05.10.02. The flaw manifests in the improper handling of Access Control List (ACL) inheritance mechanisms for default entries, particularly default:class:, default:other:, and default:user: entries. This represents a critical security weakness that directly impacts the integrity and confidentiality of file system access controls.
The technical implementation flaw occurs when the VxFS file system processes directory inheritance for default ACL entries. When a parent directory is configured with specific default ACL entries, the system fails to correctly propagate these permissions to newly created files and subdirectories. This misconfiguration allows local users to exploit the inheritance mechanism by creating new files or directories within a parent directory that has been improperly configured, thereby bypassing intended access restrictions. The vulnerability stems from a failure in the VxFS kernel module to properly validate and enforce ACL inheritance rules during directory creation operations.
From an operational perspective, this vulnerability poses significant risks to system security and data protection. Local users who can access a parent directory with misconfigured default ACL entries can escalate their privileges and gain unauthorized access to resources that should be restricted. The impact extends beyond simple privilege escalation to potentially allow data exfiltration, modification of sensitive files, and disruption of system operations. The vulnerability affects the fundamental security model of the file system, undermining the principle of least privilege and potentially enabling attackers to establish persistent access to system resources.
The vulnerability maps to CWE-276, which describes improper default permissions, and aligns with ATT&CK technique T1068, which covers "Exploitation for Privilege Escalation." Organizations using affected VxFS versions should immediately apply the relevant HPE security patches and updates. System administrators should conduct thorough audits of directory ACL configurations, particularly focusing on default entries, and implement monitoring for unusual file creation patterns. The recommended mitigation strategy includes applying the official HP-UX patches, reviewing and correcting default ACL configurations, and implementing additional access control monitoring to detect potential exploitation attempts. This vulnerability demonstrates the critical importance of proper ACL inheritance implementation in enterprise file systems and highlights the need for comprehensive security testing of core operating system components.