CVE-2012-1090 in Linux
Summary
by MITRE
The cifs_lookup function in fs/cifs/dir.c in the Linux kernel before 3.2.10 allows local users to cause a denial of service (OOPS) via attempted access to a special file, as demonstrated by a FIFO.
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Analysis
by VulDB Data Team • 03/21/2021
The vulnerability described in CVE-2012-1090 represents a critical denial of service flaw within the Linux kernel's CIFS (Common Internet File System) implementation. This issue affects systems running Linux kernel versions prior to 3.2.10 and specifically targets the cifs_lookup function located in fs/cifs/dir.c. The vulnerability arises from insufficient input validation and error handling when processing special file types, particularly FIFO (First In, First Out) named pipes. The flaw demonstrates how improper handling of file system operations can lead to system instability and complete service disruption.
The technical root cause of this vulnerability lies in the cifs_lookup function's inability to properly handle special file access attempts without adequate error checking mechanisms. When a local user attempts to access a special file such as a FIFO through the CIFS file system, the function fails to validate the file type or handle the access request appropriately. This leads to a kernel panic or OOPS (Oops error) which results in the system becoming unresponsive and requiring manual reboot. The vulnerability is particularly concerning because it can be exploited by any local user with access to the system, making it a significant security risk in multi-user environments.
From an operational impact perspective, this vulnerability creates substantial risks for system availability and stability. The denial of service condition can be triggered simply by attempting to access a FIFO file through CIFS mounts, requiring no special privileges beyond basic local access. This makes the vulnerability particularly dangerous in production environments where system uptime is critical. Organizations using affected kernel versions face potential service interruptions that could impact business operations, especially in environments where CIFS shares are actively used for file access and collaboration. The vulnerability also represents a potential vector for attackers to disrupt services, as the system crash can occur without any indication of malicious activity.
The vulnerability aligns with CWE-20, "Improper Input Validation," and demonstrates how inadequate validation of file access operations can lead to system instability. From an ATT&CK framework perspective, this represents a privilege escalation and denial of service technique that can be leveraged by adversaries to disrupt system operations. The exploitability of this vulnerability is enhanced by the fact that it requires minimal privileges and can be triggered through normal file access patterns. Organizations should prioritize patching affected systems to address this vulnerability, as the Linux kernel 3.2.10 and later versions contain the necessary fixes to prevent the improper handling of special file access through CIFS. Additionally, system administrators should monitor for any unusual access patterns that might indicate exploitation attempts and implement proper access controls to limit local user privileges where possible. The remediation process should include comprehensive testing of patched systems to ensure that the vulnerability has been fully resolved without introducing compatibility issues with existing CIFS implementations.