CVE-2009-1250 in OpenAFS
Summary
by MITRE
The cache manager in the client in OpenAFS 1.0 through 1.4.8 and 1.5.0 through 1.5.58, and IBM AFS 3.6 before Patch 19, on Linux allows remote attackers to cause a denial of service (system crash) via an RX response with a large error-code value that is interpreted as a pointer and dereferenced, related to use of the ERR_PTR macro.
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Analysis
by VulDB Data Team • 09/01/2019
The vulnerability described in CVE-2009-1250 represents a critical buffer overflow condition within the cache manager component of OpenAFS and IBM AFS implementations. This flaw exists in versions ranging from OpenAFS 1.0 through 1.4.8 and 1.5.0 through 1.5.58, alongside IBM AFS 3.6 before Patch 19, specifically affecting Linux operating systems. The vulnerability stems from improper handling of error codes within the RX protocol implementation, creating a scenario where maliciously crafted network responses can trigger system instability.
The technical root cause of this vulnerability lies in the improper interpretation of error codes as memory pointers through the ERR_PTR macro usage. When the cache manager processes an RX response containing an unusually large error-code value, the system treats this numeric value as a memory address pointer rather than a simple error indicator. This misinterpretation leads to a dereference operation on an invalid memory location, causing the kernel to crash and resulting in a complete system denial of service. The flaw demonstrates a classic improper input validation issue that falls under CWE-125, which describes out-of-bounds read conditions, and more specifically relates to CWE-787, representing out-of-bounds write vulnerabilities that can occur when pointer values are incorrectly interpreted as addresses.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be exploited remotely without authentication requirements, making it particularly dangerous in networked environments. Attackers can craft malicious RX responses that, when processed by vulnerable systems, will cause immediate system crashes and require manual intervention to restore normal operations. This type of vulnerability directly maps to ATT&CK technique T1499.004, which covers network denial of service attacks, and represents a significant threat to availability in distributed file systems. The vulnerability affects not just individual systems but can potentially disrupt entire networked environments where AFS services are utilized, as the crash can cascade through dependent services and applications.
Mitigation strategies for this vulnerability require immediate patching of affected systems with the appropriate security updates from OpenAFS or IBM AFS vendors. Organizations should prioritize updating to patched versions of these software implementations, as the vulnerability exists in multiple major releases and affects both open-source and commercial implementations. Additionally, network segmentation and firewall rules can be implemented to limit exposure to untrusted networks, though this does not eliminate the risk entirely. System administrators should also consider implementing monitoring solutions to detect anomalous RX protocol traffic patterns that might indicate exploitation attempts. The fix typically involves proper validation of error code values before attempting pointer dereference operations, ensuring that numeric error values are properly bounded and validated against expected ranges rather than being directly interpreted as memory addresses. This vulnerability serves as a reminder of the critical importance of proper input validation and memory management in kernel-level code, particularly in distributed systems where availability is paramount.