CVE-2011-1160 in Linux
Summary
by MITRE
The tpm_open function in drivers/char/tpm/tpm.c in the Linux kernel before 2.6.39 does not initialize a certain buffer, which allows local users to obtain potentially sensitive information from kernel memory via unspecified vectors.
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Analysis
by VulDB Data Team • 12/05/2021
The vulnerability identified as CVE-2011-1160 resides within the Linux kernel's Trusted Platform Module (TPM) subsystem, specifically in the tpm_open function located in drivers/char/tpm/tpm.c. This flaw represents a classic case of uninitialized memory exposure that can lead to information disclosure, making it particularly concerning for systems relying on kernel security mechanisms. The vulnerability affects Linux kernel versions prior to 2.6.39, indicating a long-standing issue that was not addressed until the subsequent kernel release.
The technical nature of this vulnerability stems from the improper initialization of a buffer within the tpm_open function. When the TPM character device is opened, the function fails to properly initialize certain memory buffers before use, creating a scenario where uninitialized kernel memory contents may be inadvertently exposed to userspace applications. This buffer initialization failure occurs during the device open operation, which means that any process attempting to open the TPM device could potentially read sensitive data that was previously stored in the uninitialized memory locations. The unspecified vectors mentioned in the description suggest that the information disclosure could occur through various access paths or interfaces within the TPM subsystem.
From an operational perspective, this vulnerability presents a significant risk to system security as it allows local users to potentially extract sensitive information from kernel memory. The disclosed information could include cryptographic keys, session data, system configuration details, or other confidential data that should remain protected within kernel space. Attackers could exploit this vulnerability to gain insights into the system's internal state, potentially aiding in more sophisticated attacks targeting the TPM subsystem or other kernel components. The local nature of the vulnerability means that it requires local system access, but this is often sufficient for attackers who have already compromised a system or for privilege escalation attacks.
The vulnerability maps to CWE-457: "Use of Uninitialized Variable" which is a well-documented weakness in software security that occurs when a variable is used without being properly initialized. This weakness is particularly dangerous in kernel space where uninitialized memory can contain sensitive data from previous operations or system states. The attack surface is further enhanced by the ATT&CK framework's concept of privilege escalation through kernel vulnerabilities, where local users can leverage such information disclosure flaws to gain deeper system access. The TPM subsystem itself is designed to provide hardware-based security services, making the exposure of kernel memory contents particularly concerning for systems relying on TPM for secure key storage and authentication mechanisms.
Mitigation strategies for CVE-2011-1160 primarily focus on upgrading to Linux kernel versions 2.6.39 or later where the buffer initialization issue has been resolved. System administrators should prioritize kernel updates as part of their regular security maintenance procedures, particularly for systems that have TPM hardware installed or that rely on TPM-based security services. Additionally, organizations should implement monitoring for unauthorized access attempts to TPM devices and consider disabling TPM functionality if it is not required for system operations. The fix implemented in the kernel involves proper initialization of the affected buffer before it is used, ensuring that no sensitive kernel memory contents are inadvertently exposed to userspace processes during TPM device access operations.