CVE-2007-3513 in Linux
Summary
by MITRE
The lcd_write function in drivers/usb/misc/usblcd.c in the Linux kernel before 2.6.22-rc7 does not limit the amount of memory used by a caller, which allows local users to cause a denial of service (memory consumption).
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Analysis
by VulDB Data Team • 07/20/2021
The vulnerability identified as CVE-2007-3513 resides within the Linux kernel's USB LCD driver component, specifically in the lcd_write function located in drivers/usb/misc/usblcd.c. This flaw represents a classic case of inadequate input validation and resource management that enables malicious local users to exploit memory consumption patterns for denial of service attacks. The vulnerability affects Linux kernel versions prior to 2.6.22-rc7, indicating it was present in a significant portion of the kernel's release cycle and likely exploited in various environments where USB LCD devices were utilized.
The technical root cause of this vulnerability stems from the lcd_write function's failure to impose reasonable limits on memory allocation during device operations. When a local user invokes the lcd_write function, the kernel allocates memory without proper bounds checking, allowing for unbounded memory consumption that can rapidly exhaust available system resources. This memory allocation behavior creates a potential for resource exhaustion attacks where malicious processes can continuously allocate memory until system stability is compromised. The vulnerability operates at the kernel level, meaning it can be exploited by any local user with access to the USB LCD device interface, making it particularly dangerous in multi-user environments where privilege escalation might not be required.
The operational impact of CVE-2007-3513 extends beyond simple denial of service conditions, as it can severely degrade system performance and potentially render the entire system unusable. When exploited, the vulnerability allows attackers to consume memory resources at an uncontrolled rate, leading to system instability, application crashes, and in severe cases, complete system lockups. The attack vector requires only local access to the system, making it accessible to users who may not possess elevated privileges, which increases the attack surface and potential impact. This vulnerability aligns with CWE-770, which describes the allocation of resources without limits or appropriate checks, and represents a clear violation of secure coding practices that should prevent unbounded resource consumption in kernel modules.
Mitigation strategies for this vulnerability primarily focus on upgrading to kernel versions 2.6.22-rc7 or later, where the memory allocation limits have been properly implemented. System administrators should also consider implementing monitoring solutions to detect unusual memory consumption patterns that might indicate exploitation attempts. Additionally, the principle of least privilege should be enforced by restricting access to USB LCD devices where possible, and kernel module loading should be restricted to prevent unauthorized access to vulnerable components. From an ATT&CK framework perspective, this vulnerability maps to T1499.004, which covers resource exhaustion attacks, and T1068, which involves local privilege escalation through kernel vulnerabilities. The vulnerability also demonstrates the importance of proper input validation and resource management in kernel space, as highlighted in various security frameworks that emphasize the need for bounded resource allocation in critical system components.