CVE-2011-1021 in Linux
Summary
by MITRE
drivers/acpi/debugfs.c in the Linux kernel before 3.0 allows local users to modify arbitrary kernel memory locations by leveraging root privileges to write to the /sys/kernel/debug/acpi/custom_method file. NOTE: this vulnerability exists because of an incomplete fix for CVE-2010-4347.
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Analysis
by VulDB Data Team • 09/02/2024
The vulnerability described in CVE-2011-1021 represents a critical privilege escalation flaw within the Linux kernel's ACPI debugfs implementation. This issue affects kernel versions prior to 3.0 and stems from an incomplete remediation of a previously identified vulnerability CVE-2010-4347. The core problem manifests through the /sys/kernel/debug/acpi/custom_method file which provides an interface for debugging ACPI methods but lacks proper access controls and input validation mechanisms. When a local user with root privileges attempts to write to this specific debugfs file, the kernel fails to properly validate the input data, allowing arbitrary memory modifications that can be exploited to gain deeper system control.
The technical exploitation of this vulnerability relies on the fundamental flaw in kernel memory management where the debugfs implementation does not adequately sanitize user input before processing it as kernel memory operations. This creates a direct pathway for memory corruption through controlled write operations that bypass normal kernel security boundaries. The vulnerability specifically targets the ACPI subsystem's debug interface, which is designed for development and troubleshooting purposes but is exposed in production environments without proper safeguards. The incomplete fix for CVE-2010-4347 suggests that the original remediation efforts were insufficient to address all potential attack vectors, leaving residual weaknesses in the kernel's memory protection mechanisms.
From an operational perspective, this vulnerability poses significant risks to system integrity and security posture since it allows a local attacker with root privileges to directly manipulate kernel memory structures. The impact extends beyond simple privilege escalation as it can potentially enable arbitrary code execution within kernel space, leading to complete system compromise. The vulnerability's exploitation requires only local root access, making it particularly dangerous in multi-tenant environments or systems where privilege separation is not properly enforced. This type of vulnerability directly violates the principle of least privilege and undermines kernel security models that depend on proper memory isolation between user and kernel spaces.
The security implications of CVE-2011-1021 align with CWE-787, which describes out-of-bounds writes, and can be categorized under ATT&CK technique T1068, which involves privilege escalation through local exploits. Organizations should implement immediate patching strategies to upgrade to kernel versions 3.0 or later where this vulnerability has been properly addressed. Additional mitigations include restricting access to debugfs interfaces, disabling unnecessary kernel debugging features in production environments, and implementing proper monitoring for suspicious write operations to kernel debug files. System administrators should also consider implementing kernel lockdown mechanisms and ensuring that debug interfaces are only accessible in controlled development environments where proper access controls are in place. The vulnerability serves as a reminder of the importance of thorough vulnerability remediation and the potential for incomplete fixes to leave systems exposed to further exploitation.