CVE-2011-1162 in Linux
Summary
by MITRE
The tpm_read function in the Linux kernel 2.6 does not properly clear memory, which might allow local users to read the results of the previous TPM command.
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Analysis
by VulDB Data Team • 11/29/2021
The vulnerability identified as CVE-2011-1162 resides within the Linux kernel version 2.6 and specifically affects the tpm_read function implementation. This flaw represents a critical memory management issue that directly impacts the Trusted Platform Module (TPM) subsystem, which is designed to provide hardware-based security features for cryptographic operations and system integrity verification. The TPM is a standardized hardware component that stores cryptographic keys, passwords, and certificates while maintaining their confidentiality and integrity through dedicated security mechanisms. When the kernel fails to properly clear memory during TPM operations, it creates a potential information disclosure risk that could compromise the security assurances typically provided by the TPM hardware.
The technical flaw manifests in the improper memory clearing behavior of the tpm_read function, which is responsible for reading data from TPM devices. In normal operation, when a TPM command is executed, the kernel allocates memory buffers to store the command results and subsequent responses. However, in this vulnerability, the memory allocated for previous TPM command results is not adequately cleared before new data is written to the same memory locations. This memory leakage allows subsequent TPM operations to potentially access residual data from prior commands that may contain sensitive cryptographic information, authentication tokens, or other confidential data processed by the TPM subsystem.
The operational impact of this vulnerability extends beyond simple information disclosure, as it undermines the fundamental security assumptions of TPM implementations. Local attackers with access to the system can exploit this flaw to potentially recover sensitive information from previous TPM operations, including cryptographic keys, authentication credentials, or system configuration data that was processed by the TPM. This vulnerability particularly affects systems where TPM is used for secure boot processes, disk encryption, or other security-critical functions that rely on the confidentiality of TPM-processed data. The attack vector is relatively straightforward since it requires only local system access, making it a significant concern for systems where privilege escalation or unauthorized access might occur.
From a cybersecurity perspective, this vulnerability aligns with CWE-248, which addresses the improper handling of memory or resources, and represents a clear violation of secure coding practices for memory management. The ATT&CK framework categorizes this vulnerability under privilege escalation and credential access tactics, as it enables attackers to extract sensitive information that could facilitate further compromise of the system. The vulnerability also relates to the broader category of information disclosure attacks, where residual data from previous operations is inadvertently exposed to unauthorized parties. System administrators and security professionals should consider this vulnerability as part of their comprehensive security posture assessment, particularly in environments where TPM-based security features are critical for system integrity and data protection. The recommended mitigation involves applying the appropriate kernel security patches that properly implement memory clearing mechanisms in the TPM subsystem, ensuring that all previous command results are adequately cleared before new operations begin.