CVE-2010-4258 in Linux
Summary
by MITRE
The do_exit function in kernel/exit.c in the Linux kernel before 2.6.36.2 does not properly handle a KERNEL_DS get_fs value, which allows local users to bypass intended access_ok restrictions, overwrite arbitrary kernel memory locations, and gain privileges by leveraging a (1) BUG, (2) NULL pointer dereference, or (3) page fault, as demonstrated by vectors involving the clear_child_tid feature and the splice system call.
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Analysis
by VulDB Data Team • 11/19/2024
The vulnerability described in CVE-2010-4258 represents a critical privilege escalation flaw within the Linux kernel's memory management subsystem. This issue resides in the do_exit function located in kernel/exit.c, where improper handling of the KERNEL_DS get_fs value creates a pathway for local attackers to circumvent kernel access controls. The vulnerability specifically affects Linux kernel versions prior to 2.6.36.2, making it a significant concern for systems running older kernel versions. The flaw operates at the kernel level, where the get_fs() function is responsible for managing the kernel's memory access permissions, and KERNEL_DS represents a specific data segment descriptor that should enforce strict access controls.
The technical exploitation of this vulnerability occurs through three primary vectors that leverage different kernel subsystems. The first vector involves BUG conditions, where the kernel's internal error handling mechanisms fail to properly validate memory access permissions when transitioning between user and kernel space. The second vector exploits NULL pointer dereferences, which occur when kernel code attempts to access memory locations that have not been properly initialized or validated. The third vector targets page fault handling mechanisms, where improper memory management during fault resolution allows attackers to manipulate kernel memory locations. The demonstration of this vulnerability specifically involves the clear_child_tid feature and the splice system call, both of which interact with kernel memory management in ways that expose the improper get_fs handling.
The operational impact of CVE-2010-4258 is severe and far-reaching, as it enables local users to achieve privilege escalation from user-level to kernel-level execution. This capability allows attackers to overwrite arbitrary kernel memory locations, effectively providing them with complete control over the system's kernel space. The vulnerability essentially undermines the fundamental security model of the Linux kernel by bypassing access_ok restrictions that are designed to prevent unauthorized memory access. Attackers can leverage this flaw to execute arbitrary code with kernel privileges, potentially leading to complete system compromise, data theft, or persistent backdoor installation. The implications extend beyond individual system security, as compromised systems can be used as launch points for broader network attacks.
This vulnerability maps directly to CWE-264, which describes permissions, privileges, and access controls issues in software systems, specifically highlighting the improper handling of kernel memory access permissions. The attack pattern aligns with ATT&CK technique T1068, which focuses on local privilege escalation through kernel exploits. The vulnerability also relates to CWE-125, which addresses out-of-bounds read conditions that can occur when memory access validation is bypassed. The exploitability of this vulnerability is enhanced by the fact that it requires no special privileges to initiate, making it particularly dangerous as it can be exploited by any local user with shell access. The three demonstrated vectors provide multiple attack pathways that increase the probability of successful exploitation and make the vulnerability particularly resilient to traditional security controls.
Mitigation strategies for CVE-2010-4258 primarily focus on kernel version updates and system hardening measures. The most effective immediate solution involves upgrading to Linux kernel version 2.6.36.2 or later, where the improper get_fs handling has been corrected. System administrators should also implement kernel hardening measures including disabling unnecessary kernel features, applying security modules like grsecurity, and configuring proper access controls. Additional mitigations include monitoring for suspicious kernel memory access patterns, implementing intrusion detection systems, and conducting regular security audits. The vulnerability highlights the importance of proper kernel memory management and access control validation, particularly in functions that handle process termination and memory cleanup operations. Organizations should also consider implementing kernel module signing requirements and maintaining up-to-date security patches to prevent exploitation of similar vulnerabilities in the future.