CVE-2015-3285 in OpenAFS
Summary
by MITRE
The pioctl for the OSD FS command in OpenAFS before 1.6.13 uses the wrong pointer when writing the results of the RPC, which allows local users to cause a denial of service (memory corruption and kernel panic) via a crafted OSD FS command.
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Analysis
by VulDB Data Team • 11/05/2017
The vulnerability described in CVE-2015-3285 represents a critical memory corruption flaw within the OpenAFS distributed file system implementation. This issue specifically affects the pioctl function responsible for handling OSD FS commands, which are essential for managing storage operations within the OpenAFS environment. The flaw exists in versions prior to 1.6.13 and demonstrates a fundamental pointer management error that can be exploited by local attackers to execute malicious code leading to system instability. The OpenAFS system, widely deployed in enterprise environments for providing distributed file services, becomes vulnerable to this type of attack that can compromise the integrity of the kernel space operations. This vulnerability directly impacts the availability and stability of the file system services, potentially causing complete system outages that affect numerous users and applications relying on the distributed storage infrastructure.
The technical root cause of this vulnerability stems from improper pointer handling within the RPC result writing mechanism of the pioctl function. When processing OSD FS commands, the system incorrectly uses a memory pointer that points to an invalid memory location or incorrect data structure during the response generation phase. This pointer mismanagement leads to memory corruption that can trigger kernel panic conditions when the corrupted memory is accessed or modified. The flaw operates at the kernel level where the system's core file operations are handled, making it particularly dangerous as it can result in complete system crashes. According to CWE classification, this represents a CWE-121: Stack-based Buffer Overflow, though it manifests more specifically as a pointer dereference error that results in memory corruption rather than traditional buffer overflow conditions. The vulnerability demonstrates the critical importance of proper memory management and pointer validation in kernel space code where even minor errors can lead to catastrophic system failures.
The operational impact of this vulnerability extends beyond simple denial of service scenarios to encompass potential system compromise and data integrity threats. Local users with access to the system can craft specific OSD FS commands that exploit the pointer error to cause memory corruption, leading to kernel panics that require system rebooting. This type of attack can be particularly devastating in enterprise environments where OpenAFS is used for critical file storage services, as it can result in extended downtime and potential data loss. The vulnerability creates opportunities for attackers to escalate privileges or cause persistent service disruptions that can affect thousands of users simultaneously. From an ATT&CK framework perspective, this vulnerability aligns with T1068: Exploitation for Privilege Escalation and T1499: Endpoint Denial of Service, as it allows local users to perform actions that can compromise system availability and potentially gain elevated privileges through kernel-level memory corruption. The impact is particularly severe in high-availability environments where such disruptions can lead to significant business continuity issues.
Mitigation strategies for CVE-2015-3285 primarily focus on upgrading to OpenAFS version 1.6.13 or later, which contains the necessary patches to correct the pointer handling error in the pioctl function. System administrators should prioritize patching all affected OpenAFS servers and clients to prevent exploitation of this vulnerability. Additional security measures include implementing strict access controls to limit local user privileges on systems running OpenAFS, monitoring for unusual OSD FS command usage patterns, and maintaining regular system backups to ensure rapid recovery from potential exploitation attempts. The vulnerability highlights the importance of thorough code review processes, particularly for kernel-level operations that handle RPC communications and memory management. Organizations should also consider implementing intrusion detection systems that can monitor for suspicious RPC command patterns and memory access anomalies that may indicate exploitation attempts. Regular security audits and vulnerability assessments should be conducted to identify similar pointer management issues in other kernel modules or system components that could present similar risks. The fix implemented in version 1.6.13 specifically addresses the incorrect pointer usage by ensuring proper memory allocation and validation before writing RPC results, thereby preventing the memory corruption conditions that previously led to kernel panics and system instability.