CVE-2007-3851 in Linux
Summary
by MITRE
The drm/i915 component in the Linux kernel before 2.6.22.2, when used with i965G and later chipsets, allows local users with access to an X11 session and Direct Rendering Manager (DRM) to write to arbitrary memory locations and gain privileges via a crafted batchbuffer.
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Analysis
by VulDB Data Team • 07/26/2019
The vulnerability identified as CVE-2007-3851 represents a critical privilege escalation flaw within the Linux kernel's graphics subsystem, specifically affecting the drm/i915 driver component. This vulnerability exists in kernel versions prior to 2.6.22.2 and particularly impacts Intel i965G and subsequent chipset architectures. The flaw resides in how the kernel handles batchbuffer operations within the Direct Rendering Manager framework, creating a pathway for local attackers to execute arbitrary code with elevated privileges.
The technical mechanism of this vulnerability involves the improper validation of batchbuffer operations within the i915 graphics driver. When an X11 session with DRM access is established, attackers can craft malicious batchbuffer commands that bypass normal memory protection mechanisms. This allows them to write to arbitrary memory locations, effectively circumventing kernel memory management protections. The vulnerability stems from insufficient bounds checking and memory address validation during batchbuffer processing, enabling attackers to manipulate graphics hardware registers and memory mappings directly through the DRM interface.
The operational impact of this vulnerability is severe as it transforms a local user with basic X11 session access into a privileged attacker capable of executing code at kernel level. This privilege escalation enables attackers to bypass standard security controls, potentially leading to complete system compromise. The vulnerability affects systems where the i965G graphics chipset is present, which includes many desktop and laptop computers from the mid-2000s era. Attackers can exploit this through legitimate graphics operations within their existing session, making detection more difficult compared to external attacks.
This vulnerability aligns with CWE-121, which addresses stack-based buffer overflow conditions, and relates to ATT&CK technique T1068, which covers privilege escalation through local exploitation. The flaw demonstrates how graphics drivers can serve as attack vectors for kernel-level privilege escalation, highlighting the importance of input validation in device drivers. Mitigation strategies include applying kernel updates to version 2.6.22.2 or later, implementing proper access controls for DRM devices, and restricting X11 session privileges for untrusted users. Additionally, system administrators should consider disabling unnecessary graphics acceleration features and monitoring for suspicious batchbuffer operations that could indicate exploitation attempts.