CVE-2005-1369 in Linux
Summary
by MITRE
The (1) it87 and (2) via686a drivers in I2C for Linux 2.6.x before 2.6.11.8, and 2.6.12 before 2.6.12-rc2, create the sysfs "alarms" file with write permissions, which allows local users to cause a denial of service (CPU consumption) by attempting to write to the file, which does not have an associated store function.
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Analysis
by VulDB Data Team • 06/06/2019
The vulnerability described in CVE-2005-1369 represents a significant security flaw in the Linux kernel's hardware monitoring subsystem, specifically affecting the it87 and via686a drivers within the I2C framework. This issue stems from improper permission handling in the sysfs interface, where the alarms file is created with write permissions despite lacking a corresponding store function to process write operations. The vulnerability exists in Linux kernel versions prior to 2.6.11.8 and 2.6.12-rc2, making it a long-standing issue that affected numerous systems running older kernel versions. The problem manifests as a denial of service condition that can consume excessive CPU resources, potentially rendering systems unstable or unresponsive.
The technical implementation of this vulnerability involves the sysfs filesystem interface within the Linux kernel, which provides a way for kernel modules to expose their internal data structures to userspace. In this case, the it87 and via686a drivers create a sysfs "alarms" file that allows write access but fails to implement the necessary store function to handle write operations properly. When local users attempt to write to this file, the kernel's sysfs subsystem cannot process the write request appropriately because there is no associated function to handle the operation, leading to resource exhaustion. This type of vulnerability falls under CWE-276, which addresses improper file permissions, and represents a classic example of a missing validation or handling mechanism in kernel space.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as it can be exploited by malicious local users to consume system resources and potentially cause system instability. Attackers can repeatedly write to the alarms file, causing the kernel to process these invalid write operations continuously, which results in high CPU utilization. This condition can be particularly problematic in server environments where sustained high CPU usage can affect service availability and overall system performance. The vulnerability demonstrates the importance of proper interface design in kernel modules, where the presence of writable sysfs entries should always be accompanied by appropriate validation and handling mechanisms.
Mitigation strategies for CVE-2005-1369 primarily involve updating to patched kernel versions where the sysfs file permissions have been corrected and proper store functions have been implemented for the alarms file. System administrators should ensure that all systems running affected kernel versions are updated promptly to prevent exploitation. Additionally, implementing proper access controls and monitoring for unusual sysfs file access patterns can help detect potential exploitation attempts. The vulnerability highlights the need for comprehensive testing of kernel modules, particularly those that expose interfaces to userspace, and the importance of following security best practices in kernel development. Organizations should also consider implementing runtime protection mechanisms and regular security audits to identify similar issues in their kernel configurations, aligning with ATT&CK technique T1068 which addresses local privilege escalation through kernel vulnerabilities.