CVE-2011-2494 in Linux
Summary
by MITRE
kernel/taskstats.c in the Linux kernel before 3.1 allows local users to obtain sensitive I/O statistics by sending taskstats commands to a netlink socket, as demonstrated by discovering the length of another user s password.
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Analysis
by VulDB Data Team • 12/03/2021
The vulnerability identified as CVE-2011-2494 resides within the Linux kernel's taskstats functionality, specifically in the kernel/taskstats.c file. This flaw represents a privilege escalation and information disclosure issue that affects Linux kernel versions prior to 3.1. The vulnerability stems from insufficient access controls within the taskstats netlink socket interface, which is designed to provide I/O statistics for processes and tasks running on the system. The taskstats subsystem was intended to offer monitoring capabilities for system administrators and applications to track resource usage, but the implementation contained a critical design flaw that allowed unauthorized access to sensitive data.
The technical mechanism of this vulnerability involves the taskstats netlink socket interface, which operates using the NETLINK_GENERIC protocol family. When local users send specially crafted taskstats commands to this socket, they can bypass normal access controls and retrieve detailed I/O statistics for processes owned by other users. This occurs because the kernel does not properly validate the credentials of the sender or enforce appropriate access restrictions when processing these commands. The flaw enables attackers to gather information about other users' processes, including file access patterns and potentially sensitive data such as password lengths, which can be inferred from I/O statistics and timing information.
The operational impact of CVE-2011-2494 is significant as it provides local attackers with a method to perform reconnaissance and information gathering without requiring elevated privileges. The ability to discover password lengths through I/O statistics demonstrates the severity of the information disclosure, as this type of data can be used in password cracking attempts or to understand user behavior patterns. Attackers can exploit this vulnerability to map the activity of other users on the system, identify running processes, and potentially determine the presence of sensitive applications or data access patterns. The vulnerability essentially undermines the principle of process isolation and user privacy within the Linux kernel, allowing unauthorized data access that could lead to further exploitation or compromise.
This vulnerability maps directly to CWE-200, which addresses "Information Exposure," and CWE-264, which covers "Permissions, Privileges, and Access Controls." The issue also aligns with ATT&CK technique T1083, "File and Directory Discovery," as it enables unauthorized access to process information that would normally be restricted. The vulnerability demonstrates the importance of proper input validation and access control implementation in kernel-level code. The fix implemented in kernel version 3.1 involved strengthening the access control checks within the taskstats subsystem, ensuring that only authorized processes can retrieve statistics for other users' processes. Organizations should ensure their systems are updated to kernel versions that contain this patch, as the vulnerability remains exploitable in older versions and represents a fundamental flaw in the kernel's privilege management system. The vulnerability also underscores the need for comprehensive security reviews of kernel subsystems that handle inter-process communication and system monitoring functions.