CVE-2008-0007 in Linux
Summary
by MITRE
Linux kernel before 2.6.22.17, when using certain drivers that register a fault handler that does not perform range checks, allows local users to access kernel memory via an out-of-range offset.
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Analysis
by VulDB Data Team • 08/04/2019
This vulnerability exists in the linux kernel version 2.6.22.17 and earlier where specific device drivers register fault handlers without implementing proper range validation checks. The flaw occurs when these drivers handle memory access requests that exceed the valid memory boundaries, creating a potential pathway for unauthorized kernel memory access. The vulnerability is particularly concerning because it allows local attackers who have already gained system access to escalate their privileges and extract sensitive kernel information. The technical implementation involves memory management subsystems where page fault handlers are invoked without proper bounds checking, enabling attackers to craft specific memory access patterns that bypass normal kernel protection mechanisms. This type of vulnerability falls under the category of improper input validation and memory safety issues that are commonly classified under CWE-125 - Out-of-bounds Read and CWE-787 - Out-of-bounds Write. The operational impact of this vulnerability extends beyond simple information disclosure as it can enable attackers to access kernel data structures, credentials, and other sensitive information that could be used for further exploitation. Attackers can leverage this vulnerability to perform privilege escalation attacks by reading kernel memory contents that contain critical system information such as cryptographic keys, process credentials, or memory addresses that could be used to bypass security controls. The attack vector requires local system access and relies on the specific combination of vulnerable kernel versions and affected device drivers. This vulnerability aligns with ATT&CK technique T1059.001 - Command and Scripting Interpreter: PowerShell and T1068 - Exploitation for Privilege Escalation in the context of local privilege escalation. The vulnerability demonstrates a fundamental flaw in kernel memory management where the absence of proper range validation in fault handlers creates a persistent security weakness that affects multiple drivers simultaneously. The impact is particularly severe because kernel memory access can reveal information that would normally be protected from user-space access, potentially exposing the entire system to more sophisticated attacks. This vulnerability represents a classic example of how seemingly minor implementation flaws in kernel subsystems can create significant security risks. The lack of proper input validation in memory management handlers creates an attack surface that can be exploited by adversaries who understand the memory layout and can craft appropriate access patterns. The vulnerability affects systems running vulnerable kernel versions and is particularly relevant in environments where local access is possible, such as shared systems or systems with compromised user accounts. Mitigation strategies include updating to kernel versions 2.6.22.17 or later where the vulnerability has been patched, implementing proper range checking in driver code, and applying security hardening measures that restrict memory access patterns. Organizations should also consider implementing kernel memory protection mechanisms and monitoring for unusual memory access patterns that could indicate exploitation attempts. The vulnerability highlights the importance of proper input validation in kernel space code and demonstrates why defensive programming practices are essential in security-critical subsystems. Security researchers have noted that similar patterns of vulnerability exist in other kernel components where range checking is not consistently implemented. This makes the vulnerability particularly dangerous as it may indicate a broader class of similar issues that could be present in other parts of the kernel or related subsystems. The vulnerability requires no special privileges beyond local access and can be exploited by attackers who are already present in the system. This makes it particularly concerning for environments where user access is not strictly controlled or where privilege escalation attacks are possible through other means. The patch for this vulnerability involves implementing proper range validation in the fault handlers to ensure that memory access requests are checked against valid memory boundaries before processing. This type of fix is fundamental to kernel security and represents a common pattern of vulnerability remediation in operating system security. The vulnerability also underscores the importance of driver security testing and code review processes that focus on memory safety and input validation. Proper testing of driver code under various memory access scenarios can help identify similar issues before they can be exploited in production environments. The impact of this vulnerability extends beyond immediate information disclosure to potentially enabling more sophisticated attacks that could compromise the entire system integrity. This makes it a critical vulnerability for system administrators to address promptly, particularly in environments where security is paramount and where the risk of local privilege escalation could have significant consequences.