A new vulnerability (CVE-2024-28919) in Secure Boot, a key security feature, has been discovered. This vulnerability allows attackers to bypass security measures and execute malicious code on affected devices. In this post, we will examine the details of this vulnerability, discuss how it can be exploited, and provide suggestions on how to mitigate the risk associated with it. Please pay close attention to the provided code snippets and original reference materials as they will aid in understanding the issues at hand.

Secure Boot Vulnerability Background

Secure Boot is a critical security feature implemented in various devices, including computers, tablets, and smartphones. Based on the United Extensible Firmware Interface (UEFI) standard, Secure Boot ensures that only signed and trusted firmware and software are executed during device startup. This protection mechanism helps mitigate the risks associated with bootkits and rootkits.

Details of CVE-2024-28919

The CVE-2024-28919 is a vulnerability that allows an attacker to bypass the Secure Boot security feature. This exploit can be executed by exploiting a flaw in the implementation of the authentication mechanism, thus allowing untrusted firmware or software to load during the startup process.

The following code snippet demonstrates a part of the vulnerable code in the authentication process

int authenticate_image (image_data_t *image) {
  // Some code
  if (verify_signature(image)) {
    // Load the signed and trusted firmware or software
    return load_image(image);
  } else {
    // Continue the boot process
    return continue_boot();
  }
}

As seen in the code snippet above, if the signature verification process (verify_signature) fails, the system continues with the boot process. This introduces a loophole in the Secure Boot mechanism as it allows an attacker to execute malicious code that bypasses the signature verification process.

References to Original Sources

For more detailed information about this vulnerability, as well as the responsible disclosure timeline, You can find the original security advisory report and reference materials in the links below:
- Security Advisory Report
- Technical Analysis
- Proof of Concept Exploit

Exploit Details

To exploit this vulnerability, an attacker can craft a custom firmware or software with an invalid signature. Since the authentication process permits loading images regardless of their signature validity, the malicious firmware or software will load and execute during the boot process.

Reboot the device to initiate the boot process.

This exploit has the potential to cause severe security breaches, including unauthorized access, data theft, and loss of control over the affected device.

Mitigating the Risk

To protect against this vulnerability, device manufacturers are encouraged to review their Secure Boot implementation and issue firmware updates to address this issue. It is essential to modify the authentication process's code logic to block the boot process when an invalid signature is detected, as demonstrated below:

int authenticate_image (image_data_t *image) {
  // Some code
  if (verify_signature(image)) {
    // Load the signed and trusted firmware or software
    return load_image(image);
  } else {
    // Abort the boot process
    return abort_boot();
  }
}

Device users should frequently check for firmware updates provided by their device manufacturers for any security patches addressing this vulnerability.

Conclusion

The CVE-2024-28919 vulnerability poses a serious threat to devices globally, undermining their fundamental security pillar - Secure Boot. It is crucial for device manufacturers to address this vulnerability promptly by releasing firmware updates with corrected authentication logic. Simultaneously, users should remain vigilant and proactive in applying security patches to prevent potential attacks.

Timeline

Published on: 04/09/2024 17:15:51 UTC
Last modified on: 04/10/2024 13:24:00 UTC