CVE-2011-2707 in Linux
Summary
by MITRE
The ptrace_setxregs function in arch/xtensa/kernel/ptrace.c in the Linux kernel before 3.1 does not validate user-space pointers, which allows local users to obtain sensitive information from kernel memory locations via a crafted PTRACE_SETXTREGS request.
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Analysis
by VulDB Data Team • 12/02/2021
The vulnerability identified as CVE-2011-2707 represents a critical security flaw in the Linux kernel's ptrace implementation specifically affecting the Xtensa architecture. This issue resides in the ptrace_setxregs function located within arch/xtensa/kernel/ptrace.c, where the kernel fails to properly validate user-space pointers before processing PTRACE_SETXTREGS requests. The flaw enables local attackers with process tracing capabilities to exploit this weakness and extract sensitive information from kernel memory regions that should remain protected from user-space access.
The technical implementation of this vulnerability stems from the absence of proper pointer validation mechanisms within the kernel's ptrace subsystem. When a process executes a PTRACE_SETXTREGS request, the kernel should verify that the user-space pointer provided by the requesting process points to valid memory locations within the user address space. However, the ptrace_setxregs function in affected kernel versions bypasses this crucial validation step, allowing malicious processes to supply arbitrary pointer values that can reference kernel memory locations. This lack of input sanitization creates a direct information disclosure channel that violates fundamental security principles of kernel memory protection.
From an operational perspective, this vulnerability presents significant risks to system security as it allows local users to gain unauthorized access to kernel memory contents. The information obtained through this exploit could include sensitive data such as cryptographic keys, passwords, or other confidential information stored in kernel memory. Since the vulnerability requires only local access and process tracing privileges, it can be exploited by users who have basic system access or by malicious processes running with limited privileges. This makes the attack surface particularly concerning as it can be leveraged in various attack scenarios including privilege escalation attempts or information gathering operations.
The exploitation of this vulnerability aligns with several ATT&CK framework techniques including privilege escalation and credential access. Specifically, it relates to techniques such as T1068 (Local Privilege Escalation) and T1552 (Unsecured Credentials) where attackers can leverage kernel memory access to extract sensitive information. From a CWE perspective, this vulnerability maps to CWE-125: Out-of-bounds Read, as the function reads from memory locations that are not properly validated, and potentially CWE-20: Improper Input Validation, since user-supplied pointers are not adequately checked before use. The vulnerability also demonstrates characteristics of CWE-787: Out-of-bounds Write, as malicious input could potentially cause unintended memory modifications.
Mitigation strategies for CVE-2011-2707 primarily involve upgrading to Linux kernel versions 3.1 or later where the vulnerability has been addressed through proper pointer validation in the ptrace_setxregs function. System administrators should implement the latest security patches and kernel updates to ensure protection against this specific vulnerability. Additionally, organizations should consider implementing process monitoring and anomaly detection to identify unauthorized ptrace operations that might indicate exploitation attempts. The principle of least privilege should be enforced to limit the number of processes with tracing capabilities, reducing the attack surface for potential exploitation. Regular security audits and kernel security assessments should be conducted to identify similar vulnerabilities in other kernel subsystems that might present analogous security risks.