CVE-2016-2860 in OpenAFS
Summary
by MITRE
The newEntry function in ptserver/ptprocs.c in OpenAFS before 1.6.17 allows remote authenticated users from foreign Kerberos realms to bypass intended access restrictions and create arbitrary groups as administrators by leveraging mishandling of the creator ID.
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Analysis
by VulDB Data Team • 08/19/2022
The vulnerability identified as CVE-2016-2860 resides within the OpenAFS distributed file system implementation, specifically within the ptserver component responsible for managing principal and group information. This flaw exists in versions prior to 1.6.17 and represents a critical authorization bypass that enables remote authenticated users from foreign Kerberos realms to escalate their privileges and create arbitrary groups with administrator-level permissions. The issue stems from improper handling of the creator ID parameter within the newEntry function located in ptserver/ptprocs.c, which governs how new entries are processed and validated within the principal table.
The technical implementation of this vulnerability exploits a fundamental flaw in access control validation mechanisms. When users from foreign Kerberos realms attempt to create new entries through the ptserver, the system fails to properly validate the creator ID against the expected realm boundaries. This mishandling allows malicious actors to manipulate the creator ID field to impersonate legitimate administrators, thereby circumventing the intended access restrictions that should prevent unauthorized group creation. The vulnerability specifically targets the privilege escalation path that should be restricted to authorized administrators within the same realm, creating a dangerous loophole that undermines the security model of the distributed authentication system.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it enables attackers to construct arbitrary group memberships that can be leveraged for further attacks within the OpenAFS environment. Once an attacker successfully creates a group with administrator privileges, they can potentially access restricted resources, modify access controls, and establish persistent access points within the distributed file system. This capability particularly threatens organizations that rely on OpenAFS for large-scale distributed computing environments where proper access control is essential for maintaining data integrity and security boundaries across multiple domains and user populations.
Security professionals should recognize this vulnerability as a variant of CWE-284, which addresses improper access control in software systems, and it aligns with ATT&CK technique T1078 related to valid accounts and privilege escalation. The mitigation strategy involves upgrading to OpenAFS version 1.6.17 or later, which includes proper validation of creator IDs and enhanced realm boundary checking. Organizations should also implement network segmentation to limit access to ptserver components, enforce strict authentication controls for foreign realm users, and conduct regular audits of group memberships and access controls to detect potential exploitation attempts. Additional protective measures include monitoring for unusual group creation patterns and implementing principle of least privilege enforcement for all administrative operations within the OpenAFS environment.