CVE-2022-35897 - Stack Buffer Overflow Vulnerability in Insyde InsydeH2O Leads to Arbitrary Code Execution

A newly discovered security vulnerability tagged as CVE-2022-35897 affects Insyde InsydeH2O firmware, specifically on versions with kernel 5. through 5.5. This critical vulnerability involves a stack buffer overflow that, when exploited, allows for the execution of arbitrary code on the system. The good news is that to carry out an attack, a direct SPI (Serial Peripheral Interface) modification is required as the vulnerable UEFI (Unified Extensible Firmware Interface) variables are locked at the OS level. This post intends to discuss the details of the exploit, provide a code snippet for better understanding, and share links to the original references.

Exploit Details

Insyde InsydeH2O's vulnerability arises due to specific UEFI variables that are prone to a stack overflow. These variables, SecureBootEnforce, SecureBoot, and RestoreBootSettings, are usually locked at the operating system level with read-only access. However, if an attacker can modify at least two of these three variables, the system becomes susceptible to arbitrary code execution.

An adversary would require direct SPI modification, meaning physical access to the SPI chip, to perform a successful attack. An attacker could exploit this vulnerability to execute arbitrary code, potentially leading to complete system control, unauthorized access, and data compromise.

Code Snippet

Hypothetical code snippet to demonstrate changing the values of two variables to initiate arbitrary code execution:

#include <stdio.h>

#define VARIABLE_ONE "SecureBootEnforce"
#define VARIABLE_TWO "SecureBoot"
#define VARIABLE_THREE "RestoreBootSettings"

void triggerVulnerability() {
    printf("Arbitrary code execution...\n");
}

void changeVariables(char *varOne, char *varTwo) {
    if (varOne == VARIABLE_ONE || varOne == VARIABLE_TWO || varOne == VARIABLE_THREE) {
        if (varTwo == VARIABLE_ONE || varTwo == VARIABLE_TWO || varTwo == VARIABLE_THREE) {
            if (varOne != varTwo) {
                triggerVulnerability();
            }
        }
    }
}

int main() {
    printf("CVE-2022-35897 Demonstration:\n");
    char *variableOne = VARIABLE_ONE;
    char *variableTwo = VARIABLE_TWO;
    changeVariables(variableOne, variableTwo);

    return ;
}

Please note that the above code is only for illustration purposes and does not represent a real-world exploit.

Original References

For more information regarding this vulnerability (CVE-2022-35897), please refer to the following sources:

1. Link to CVE Details page
2. Link to InsydeH2O official website

Conclusion

CVE-2022-35897 is a critical stack buffer overflow vulnerability in Insyde InsydeH2O that allows arbitrary code execution when specific UEFI variables are tampered with. While exploiting this vulnerability requires an attacker to have direct access to the SPI chip, it could lead to unauthorized access, data compromise, and full control of the affected system if successful. It is essential to keep firmware up to date and continue to monitor security alerts for affected Insyde InsydeH2O versions to protect against potential attacks utilizing this vulnerability.

Timeline

Published on: 11/21/2022 17:15:00 UTC
Last modified on: 11/30/2022 18:49:00 UTC