CVE-2021-41838 : Security Advisory and Response

An issue allowing unauthorized access to System Management Mode in Insyde InsydeH2O.

Understanding CVE-2021-41838

What is CVE-2021-41838?

CVE-2021-41838 is a vulnerability in SdHostDriver in the kernel 5.0 through 5.5 in Insyde InsydeH2O. It enables an attacker to access System Management Mode and execute arbitrary code due to a Numeric Range Comparison Without a Minimum Check.

The Impact of CVE-2021-41838

Unauthorized access to System Management Mode can lead to the execution of arbitrary code, potentially allowing an attacker to take control of the affected system.

Technical Details of CVE-2021-41838

Vulnerability Description

The vulnerability exists in SdHostDriver in the specified kernel versions, enabling an attacker to exploit an SMM callout to gain unauthorized access.

Affected Systems and Versions

Product: not applicable
Vendor: not applicable
Versions affected: not applicable

Exploitation Mechanism

The vulnerability arises from a lack of minimum check in Numeric Range Comparison, facilitating unauthorized access to the System Management Mode.

Mitigation and Prevention

Immediate Steps to Take

Apply security patches provided by the vendor promptly.
Monitor for any unauthorized access or malicious activity on the system.

Long-Term Security Practices

Implement stringent access controls to prevent unauthorized access.
Regularly update and patch systems to address known vulnerabilities.

Patching and Updates

It is crucial to install security updates and patches released by the vendor to mitigate the CVE-2021-41838 vulnerability.