CVE-2022-33909 in insyde
Summary
by MITRE • 11/15/2022
DMA transactions which are targeted at input buffers used for the HddPassword software SMI handler could cause SMRAM corruption through a TOCTOU attack. DMA transactions which are targeted at input buffers used for the software SMI handler used by the HddPassword driver could cause SMRAM corruption through a TOCTOU attack..This issue was discovered by Insyde engineering based on the general description provided by Intel's iSTARE group. Fixed in kernel Kernel 5.2: 05.27.23, Kernel 5.3: 05.36.23, Kernel 5.4: 05.44.23, Kernel 5.5: 05.52.23 https://www.insyde.com/security-pledge/SA-2022051
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Analysis
by VulDB Data Team • 06/12/2026
The vulnerability identified as CVE-2022-33909 represents a critical security flaw in the handling of System Management Interrupts within the HddPassword software SMI handler. This issue specifically targets the interaction between DMA transactions and input buffers used by the SMI handler, creating a pathway for malicious actors to compromise the System Management RAM. The vulnerability arises from a time-of-check to time-of-use condition that allows an attacker to manipulate data between the initial validation and actual processing phases, effectively bypassing intended security controls. The flaw was discovered through collaboration between Insyde engineering and Intel's iSTARE group, highlighting the interconnected nature of modern firmware security vulnerabilities. This particular weakness exists in the kernel versions 5.2 through 5.5, with specific patch dates provided for each release, demonstrating the urgency and severity of the issue. The vulnerability falls under the CWE-367 category of Time-of-Check to Time-of-Use race condition, which is a well-documented pattern in software security where the state of a resource changes between the time it is checked and when it is used, creating opportunities for exploitation. The attack vector leverages DMA capabilities, which are commonly used for high-speed data transfers between hardware components and system memory, making this particularly dangerous in environments where DMA access is permitted to potentially malicious devices.
The technical exploitation of this vulnerability occurs through a sophisticated TOCTOU attack pattern that specifically targets the SMI handler mechanism within the HddPassword driver. When DMA transactions are directed toward input buffers used by the SMI handler, the system's normal validation process can be circumvented due to the timing gap between when the buffer is checked for validity and when it is actually processed. This window of opportunity allows an attacker to modify the buffer contents between the check and use operations, potentially leading to SMRAM corruption. The SMI handler, which operates in a privileged execution context separate from the operating system, becomes a critical attack surface when vulnerable to such timing-based manipulations. The corruption of SMRAM represents a particularly severe security consequence because this memory region contains sensitive data and code that operates with the highest privilege levels, including system firmware and security-related functions. The vulnerability demonstrates how even seemingly benign driver functionality can become a critical security weakness when proper synchronization and validation mechanisms are absent. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and persistence through firmware manipulation, as it allows attackers to corrupt memory regions that are typically protected from user-level access.
The operational impact of CVE-2022-33909 extends far beyond simple data corruption, as it represents a fundamental breach in the security model of the system's firmware layer. When SMRAM becomes corrupted through this vulnerability, it can lead to complete system compromise, as the compromised memory region contains critical security functions and sensitive data that are essential for maintaining system integrity. The vulnerability's exploitation requires DMA access capabilities, which means that an attacker must already have some level of physical or network access to the system to initiate the attack, but once successful, the consequences are severe. This attack pattern can be particularly insidious because SMI handlers are designed to operate in a trusted execution environment, making them attractive targets for attackers seeking to establish persistent backdoors or escalate privileges. The timing aspect of this vulnerability means that it can be difficult to detect through traditional security monitoring approaches, as the attack occurs during legitimate system operations and the window of opportunity for exploitation is typically very brief. Organizations using affected kernel versions face significant risk of system compromise, especially in environments where DMA access is not properly restricted or monitored. The patching timeline provided by Insyde shows that this vulnerability was addressed promptly, but systems that remain unpatched continue to expose themselves to potential exploitation by threat actors who may have already developed or discovered working exploits for this specific flaw.
The mitigation strategies for CVE-2022-33909 focus on both immediate remediation through kernel updates and longer-term architectural improvements to prevent similar vulnerabilities. Organizations must prioritize updating their systems to the patched kernel versions, which were released in May 2022, ensuring that all affected systems receive the necessary security patches. The fundamental fix involves implementing proper synchronization mechanisms within the SMI handler to prevent the TOCTOU race condition, requiring that buffer validation and usage occur in a single atomic operation or with appropriate locking mechanisms. System administrators should also implement strict DMA access controls, particularly for devices that are not essential for system operation, as this reduces the attack surface available to potential adversaries. From a monitoring perspective, organizations should enhance their firmware integrity checking capabilities and implement continuous monitoring for unauthorized changes to SMRAM. The vulnerability serves as a reminder of the critical importance of secure firmware design and the need for comprehensive security testing throughout the development lifecycle. Additionally, implementing memory protection mechanisms and ensuring that SMI handlers operate with the principle of least privilege can help mitigate the impact of similar future vulnerabilities. The incident also underscores the importance of maintaining up-to-date security patches and the need for organizations to have robust vulnerability management processes in place to quickly respond to emerging threats in the firmware layer of their systems.