CVE-2007-3654 in NetBSD
Summary
by MITRE
The display driver allocattr functions in NetBSD 3.0 through 4.0_BETA2, and NetBSD-current before 20070728, allow local users to cause a denial of service (panic) via a (1) negative or (2) large value in an ioctl call, as demonstrated by the vga_allocattr function.
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Analysis
by VulDB Data Team • 09/08/2018
The vulnerability described in CVE-2007-3654 represents a critical flaw in the display driver subsystem of NetBSD operating systems, specifically affecting versions from 3.0 through 4.0_BETA2 and earlier versions of NetBSD-current. This issue manifests within the allocattr functions of the display driver framework, which are responsible for managing attribute allocations for graphics hardware. The flaw arises from insufficient input validation mechanisms within these functions, creating a pathway for local privilege escalation that results in system-wide denial of service conditions. The vulnerability is particularly concerning because it operates at the kernel level, where improper input handling can lead to system crashes and complete system panics that require manual rebooting to restore normal operations.
The technical implementation of this vulnerability stems from the absence of proper bounds checking in the ioctl system calls that interact with the vga_allocattr function. When local users submit ioctl commands containing either negative values or excessively large numerical inputs, the display driver fails to validate these parameters before processing them. This lack of input sanitization creates a buffer overflow condition or arithmetic overflow that ultimately leads to kernel panic states. The vulnerability operates under CWE-129, which specifically addresses insufficient input validation, and demonstrates how improper validation of user-supplied data can result in system instability and denial of service conditions. The attack vector requires local system access, meaning any user with login privileges can potentially exploit this vulnerability to disrupt system operations.
The operational impact of CVE-2007-3654 extends beyond simple system crashes, as it can compromise the availability of critical graphical services and potentially affect other system components that depend on proper display driver functionality. When a kernel panic occurs due to this vulnerability, the entire system becomes unresponsive and requires manual intervention to recover. This type of denial of service attack can be particularly damaging in server environments where continuous uptime is essential, as it can result in service interruptions and potential data loss. The vulnerability also aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, though in this case the attack occurs locally within the operating system rather than through network protocols.
Mitigation strategies for this vulnerability should focus on immediate patching of affected NetBSD systems to versions released after July 28, 2007, when the fix was implemented. System administrators should also implement monitoring solutions to detect unusual ioctl activity patterns that might indicate exploitation attempts. Additionally, the vulnerability highlights the importance of robust input validation in kernel-space code and demonstrates the necessity of comprehensive testing procedures for driver components. The fix typically involves implementing proper parameter validation within the allocattr functions to reject negative or excessively large values before they can cause system instability. Organizations should also consider implementing privilege separation mechanisms and limiting local user access to critical system interfaces where possible to reduce the attack surface for such vulnerabilities.