The Rise of CPU-Level Ransomware: A New Era of Undetectable Threats

Before diving into CPU-level ransomware, let’s first understand what ransomware actually is. Ransomware is a type of malicious software (malware) that locks or encrypts your files and demands a ransom to unlock them. The victim loses access to their data unless they pay the attacker. Traditionally, ransomware attacks occur at the software level—the attacker attaches ransomware to an application or file, and once downloaded and run by the user, the malware activates. These kinds of attacks are often detectable and removable by antivirus software. However, the game is now changing. Attackers are shifting their focus from software to hardware. Specifically, they are targeting something called firmware microcode.

What is Microcode?

Microcode is a tiny instruction manual written inside the CPU. It helps the processor interpret high-level machine code instructions. By modifying this microcode, attackers can make the CPU itself behave maliciously—without needing any external software or files.

What is Firmware?

Firmware is a type of software that is embedded into hardware and controls how that hardware operates. You can think of it as the "brain" that tells a device what to do. A common example is BIOS (Basic Input/Output System)—the firmware that helps your computer boot up before the operating system loads. Now imagine if that firmware is infected. In CPU-level ransomware attacks, attackers modify the firmware’s microcode so that the hardware itself behaves maliciously. This is far more dangerous than traditional attacks because:

• Firmware loads before the operating system, making it invisible to normal security tools.
• Even formatting the system or reinstalling the OS won’t remove the malware.
• The malware is embedded deep within the hardware, making detection and removal extremely difficult.

Why is CPU-Level Ransomware So dangerous?

• It cannot be detected by antivirus software.
• Survives even your OS is reinstalled.
• It controls your system from the hardware level.
• Maybe You have to replace your hardware(motherboard or CPU) fully remove it.

Firmware-Based Attacks in History

BadUSB (2014) – This attack was carried out using USB devices that were reprogrammed to behave maliciously. The firmware inside the USB was modified, making it act like a keyboard or network device to execute unauthorized commands.

Equation Group HDD Hack (2015) – In this attack, the firmware of hard drives was infected to enable permanent spying capabilities. It was attributed to a highly advanced threat actor known as the Equation Group.

LoJax (2018) – LoJax was the first known UEFI rootkit discovered in the wild. It targeted the BIOS/UEFI firmware, allowing the malware to persist even after the operating system was reinstalled or the hard drive was replaced.

CosmicStrand (2022) – This advanced malware was embedded in the UEFI firmware of the motherboard, enabling it to execute malicious code before the operating system even starts, and thus stay hidden from most security tools.

How can we Stay Protected?

• Buy Hardware from trusted sources.
• Monitor hardware activities.
• Avoid using unknown USB’s or other hardware components (they may contain malwares).
• Enable Secure Boot in your UEFI settings.
• Regularly update BIOS/UEFI firmware.

Final thoughts

We’re entering a new phase of cybersecurity where even our hardware can’t be trusted if we’re not careful. CPU-level ransomware is a warning sign that threats are evolving—and our security practices need to evolve too. This isn’t just for security experts everyone who uses a computer should understand these risks.