CVE-2018-16947 in OpenAFS
Summary
by MITRE
An issue was discovered in OpenAFS before 1.6.23 and 1.8.x before 1.8.2. The backup tape controller (butc) process accepts incoming RPCs but does not require (or allow for) authentication of those RPCs. Handling those RPCs results in operations being performed with administrator credentials, including dumping/restoring volume contents and manipulating the backup database. For example, an unauthenticated attacker can replace any volume's content with arbitrary data.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 05/16/2023
The vulnerability identified as CVE-2018-16947 represents a critical authentication flaw within the OpenAFS backup tape controller component known as butc. This issue affects versions prior to 1.6.23 and 1.8.2, creating a significant security weakness that undermines the integrity and confidentiality of the distributed file system. The flaw resides in the process's design where it accepts remote procedure calls without requiring any form of authentication, effectively creating an open door for unauthorized entities to exploit the system's administrative capabilities.
The technical implementation of this vulnerability stems from the butc process's failure to validate caller credentials before executing administrative operations. When the process receives RPC requests, it processes them without verifying the identity of the requesting entity, allowing any remote attacker to submit malicious RPC commands that are executed with elevated privileges. This design flaw directly violates fundamental security principles of least privilege and authentication enforcement, as the system operates under the assumption that all incoming RPCs are legitimate and authorized.
The operational impact of this vulnerability is severe and far-reaching within OpenAFS environments. An unauthenticated attacker can leverage this weakness to perform critical administrative functions including dumping and restoring volume contents, manipulating the backup database, and replacing volume data with arbitrary content. These capabilities enable attackers to not only access sensitive data but also to corrupt or destroy data integrity across the entire file system. The ability to substitute volume contents with malicious data poses a significant risk to data availability and system reliability, potentially leading to complete system compromise or data loss.
This vulnerability maps directly to CWE-287, which addresses improper authentication issues in software systems, and aligns with multiple ATT&CK techniques including T1078 for valid accounts and T1005 for data from local system. The attack surface is particularly concerning given that the butc process typically runs on backup servers and may be accessible over network connections, making it an attractive target for remote exploitation. Organizations using affected versions of OpenAFS face potential exposure to attackers who can leverage this weakness to gain persistent access to their distributed file systems.
The remediation strategy requires immediate deployment of patched versions of OpenAFS, specifically versions 1.6.23 or later for the 1.6.x series and 1.8.2 or later for the 1.8.x series. System administrators should also implement network segmentation to limit access to backup servers and ensure that the butc process only accepts RPC connections from trusted sources. Additional mitigations include monitoring RPC traffic for unusual patterns and implementing network-based intrusion detection systems to identify potential exploitation attempts. Organizations should conduct comprehensive security assessments to identify any potential compromise and verify that all systems have been updated to address this critical authentication vulnerability.