CVE-2021-41839 : Exploit Details and Defense Strategies

An issue was discovered in NvmExpressDxe in the kernel 5.0 through 5.5 in Insyde InsydeH2O, leading to SMM memory corruption and potential privilege escalation.

Understanding CVE-2021-41839

This CVE involves an Untrusted Pointer Dereference in NvmExpressDxe, potentially allowing an attacker to manipulate SMRAM data.

What is CVE-2021-41839?

The vulnerability in NvmExpressDxe in the Insyde InsydeH2O kernel version 5.0 through 5.5 enables unauthorized access to SMM memory, risking the integrity of the system.

The Impact of CVE-2021-41839

Exploiting this vulnerability could result in an attacker writing fixed or predictable data to SMRAM and potentially escalating privileges to SMM, compromising system security.

Technical Details of CVE-2021-41839

This section delves into the technical aspects of the CVE.

Vulnerability Description

The Untrusted Pointer Dereference in NvmExpressDxe triggers SMM memory corruption, posing a risk of unauthorized data alteration in SMRAM.

Affected Systems and Versions

Insyde InsydeH2O kernel versions 5.0 through 5.5

Exploitation Mechanism

The vulnerability allows attackers to write predictable data to SMRAM, elevating their privileges to SMM and potentially gaining control over the system.

Mitigation and Prevention

It is crucial to take immediate steps to address and prevent exploitation of CVE-2021-41839.

Immediate Steps to Take

Update to patched versions of the affected kernel to mitigate the vulnerability.
Monitor SMRAM integrity and access for any unauthorized changes.

Long-Term Security Practices

Implement secure coding practices to prevent similar memory corruption issues.
Regularly audit and assess SMM memory for any anomalies.

Patching and Updates

Stay informed about security advisories from Insyde and related vendors to apply patches promptly.