CVE-2011-2209 in Linux
Summary
by MITRE
Integer signedness error in the osf_sysinfo function in arch/alpha/kernel/osf_sys.c in the Linux kernel before 2.6.39.4 on the Alpha platform allows local users to obtain sensitive information from kernel memory via a crafted call.
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Analysis
by VulDB Data Team • 12/03/2021
The vulnerability identified as CVE-2011-2209 represents a critical integer signedness error within the Linux kernel's Alpha platform implementation, specifically affecting the osf_sysinfo function located in arch/alpha/kernel/osf_sys.c. This flaw exists in kernel versions prior to 2.6.39.4 and demonstrates a fundamental issue in how signed and unsigned integer values are handled during system information retrieval operations. The vulnerability stems from the improper handling of integer types when processing system information requests, creating a pathway for unauthorized information disclosure.
The technical exploitation of this vulnerability occurs through a crafted system call that manipulates the integer parameters passed to the osf_sysinfo function. When the kernel processes these malformed inputs, the signedness error causes the system to interpret certain memory addresses or values incorrectly, leading to the exposure of sensitive kernel memory contents. This type of error falls under CWE-191, which specifically addresses integer underflow and overflow conditions, and more broadly relates to CWE-190, which covers integer overflow and underflow. The vulnerability exploits the fundamental principle that signed integers can be manipulated to produce unexpected behavior when compared against unsigned values, particularly in contexts where memory boundaries are not properly validated.
The operational impact of this vulnerability extends beyond simple information disclosure, as local attackers with minimal privileges can potentially extract kernel memory contents that may contain sensitive data such as cryptographic keys, passwords, or other confidential information. This represents a significant security risk for systems running affected kernel versions, particularly in environments where privilege separation is not strictly enforced. The vulnerability's classification under the ATT&CK framework would place it within the Information Gathering tactic, specifically under the technique of System Information Discovery, where adversaries seek to understand the target environment and identify potential attack vectors through reconnaissance activities. The fact that this is a local privilege escalation vector means that even users with limited access can potentially gain access to kernel-level information that could be leveraged for further attacks.
Mitigation strategies for CVE-2011-2209 require immediate kernel version updates to 2.6.39.4 or later, which contain the necessary patches to address the integer signedness error in the osf_sysinfo function. System administrators should prioritize patching affected Alpha platform systems, as the vulnerability cannot be effectively mitigated through configuration changes or network-level defenses. Additionally, organizations should implement monitoring for suspicious system call patterns that might indicate exploitation attempts, particularly focusing on osf_sysinfo function calls with unusual parameter values. The patch implementation addresses the root cause by ensuring proper integer type handling and validation, preventing the signedness error from causing unintended memory access patterns. Security teams should also consider implementing privilege separation mechanisms and access controls to limit the potential impact of local users who might attempt to exploit this vulnerability, though the most effective defense remains the timely application of the kernel security update.