CVE-2007-5633 in Speedfan
Summary
by MITRE
Speedfan.sys in Alfredo Milani Comparetti SpeedFan 4.33, when used on Microsoft Windows Vista x64, allows local users to read or write arbitrary MSRs, and gain privileges and load unsigned drivers, via the (1) IOCTL_RDMSR 0x9C402438 and (2) IOCTL_WRMSR 0x9C40243C IOCTLs to \Device\speedfan, as demonstrated by an IOCTL_WRMSR action on MSR_LSTAR.
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Analysis
by VulDB Data Team • 09/10/2018
The vulnerability identified as CVE-2007-5633 resides within the Speedfan.sys kernel driver component of Alfredo Milani Comparetti SpeedFan version 4.33, specifically affecting Microsoft Windows Vista x64 systems. This represents a critical privilege escalation vulnerability that exploits weaknesses in the driver's implementation of Microsoft Windows kernel-mode device control interfaces. The flaw manifests through two specific IOCTL (Input/Output Control) commands that expose direct access to Model Specific Registers (MSRs) through the \Device\speedfan device interface, creating an attack surface that enables local adversaries to manipulate low-level system hardware components.
The technical implementation of this vulnerability leverages the Windows kernel's device driver architecture where the Speedfan.sys driver fails to properly validate or restrict access to MSR operations. When local users interact with the device through IOCTL_RDMSR (0x9C402438) and IOCTL_WRMSR (0x9C40243C) commands, they can directly read and write to any MSR within the processor's address space. The demonstration of this vulnerability specifically shows exploitation through MSR_LSTAR (Model Specific Register - Long Term Average System Time) which controls the system's interrupt handling mechanism. This particular MSR is significant because it governs the processor's response to system calls and interrupts, making it a prime target for privilege escalation attacks. The vulnerability stems from inadequate input validation and lack of proper access controls within the driver's IOCTL handling mechanism, allowing unauthorized users to bypass normal kernel security restrictions.
The operational impact of this vulnerability is severe and multifaceted, representing a complete breakdown of Windows kernel security models. Local attackers can leverage this flaw to execute arbitrary code with kernel-level privileges, effectively bypassing Windows Vista's User Access Control (UAC) and other security mitigations. The ability to read arbitrary MSRs allows attackers to extract sensitive system information, while write capabilities enable manipulation of critical processor control registers. The vulnerability also permits loading unsigned drivers, which fundamentally undermines the Windows Driver Signing requirements and allows for complete system compromise. This type of vulnerability directly maps to CWE-264, which addresses permissions, privileges, and access controls, and aligns with ATT&CK techniques involving privilege escalation through kernel exploits and driver manipulation. The attack vector requires only local system access, making it particularly dangerous as it can be exploited by malware or malicious users with basic user privileges.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term security hardening. The most effective immediate solution involves updating to a newer version of SpeedFan that properly implements access controls and does not expose MSR manipulation capabilities through user-accessible IOCTL interfaces. System administrators should also implement driver signing enforcement and disable unnecessary kernel-mode device access. The vulnerability highlights the importance of proper kernel driver security design and adherence to secure coding practices such as those recommended in the Microsoft Security Development Lifecycle. Additionally, monitoring for suspicious driver loading activities and MSR access patterns can help detect exploitation attempts. Organizations should also consider implementing kernel-mode exploit detection mechanisms and maintaining up-to-date security patches for all system components. The vulnerability serves as a stark reminder of the critical importance of proper privilege separation and access control validation in kernel-mode drivers, as specified in various security standards including those related to secure kernel programming practices and Microsoft's driver security requirements.