Security Alert: Attackers Exploit BMC Firmware Bugs to Bypass Signature Verification

[johny899]

Can you even imagine that your server could ever have its firmware hacked?! Just recently, researchers have found that bugs and exploits in Baseboard Controller Management (BMC) firmware gave attackers the ability to install services and trigger a malicious update—all while going completely unnoticed. The thought crossed my mind, “That’s literally a secret backdoor into a locked house!”

The Issues​

BMC firmware generally features some checks & balances by employing digital signatures for updates. In Supermicro BMCs, however, an attacker could exploit a couple of software bugs—or more aptly described as clever bypasses—to compromise those controls. Here is the short version:

CVEs-2025-7937: Patch Bypass

An adversary can modify the bootloader and make the BMC execute their code even after successfully installing a security patch. The adversary does not know that they are running malware and there is no apparent sign of abnormality on the BMC.

CVE-2025-6198: Signature Table Trick

Certain hackers will create a vulnerability in the signature table by splitting firmware into sections and then convincing the system everything is normal. This results in code that remains opaque during the boot process.

The Importance of It​

These vulnerabilities show that it is not enough to only check the integrity of your bootloader. Attackers can also embed themselves in other parts of the firmware and take over the system. Even the most diligent system administrators may fall victim to this.

How to Protect Your Servers​

Are you wondering what steps you can take to stay secure? One way to lower your risks is by following these recommendations:

• Make sure to update the firmware when new releases become available.
• When using the firmware, validate the SHA-256 hashes to make sure the files are valid.
• Enable hardware security features such as Root of Trust.
• Monitor the processes running on the BMC and conduct security checking as a regular part of your operations.

Alternatively, you can monitor your firmware with Binarly Transparency Platform to potentially catch unknow problems before they escalate into a problem.

Conclusion​

BMC firmware problems may not seem serious, but they are. If you maintain or operate servers, know what systems you have and lock them down. Like your home—you don't just lock your front door.