Recently, cybersecurity experts unveiled a new bootkit named HybridPetya. This novel threat is capable of circumventing UEFI Secure Boot protections, making it a critical risk to computer systems. This ransomware delivers an ominous ransom note to victims, requiring a $1,000 ransom in Bitcoin. The BitCoin wallet address associated with this ransomware is 34UNkKSGZZvf5AYbjkUa2yYYzw89ZLWxu2. Since then, it has sat empty despite having received $183.32 between February and May 2025.
The bootkit does this by generating an integer file “\EFI\Microsoft\Boot\counter” on the EFI System Partition. This file can take on three different values: 0, 1, or 2. A value of 0 indicates that the physical disk can be encrypted. Conversely, a value of 1 indicates that the disk has been previously encrypted. A value of 2 indicates that the ransom has been paid and the disk decrypted.
Exploitation of UEFI Secure Boot
HybridPetya’s method of outsmarting traditional security it’s disconcerting. Famous experts in the field confirm that this onebootkit could be at least the fourth known UEFI bootkit. It impacts its ability to skip Secure Boot protections. Previous notable examples include BlackLotus, BootKitty, and the Hyper-V Backdoor proof-of-concept.
“HybridPetya is now at least the fourth publicly known example of a real or proof-of-concept UEFI bootkit with UEFI Secure Boot bypass functionality,” – ESET.
The implications of this trend are significant. Academic researchers have only begun to scratch the surface of these vulnerabilities. The evidence is undeniable that Secure Boot bypasses are dished out like candy on Halloween by attackers and researchers alike.
“This shows that Secure Boot bypasses are not just possible – they’re becoming more common and attractive to both researchers and attackers,” – ESET.
HybridPetya uses a very unsafe approach to run arbitrary untrusted code with high level privileges, while completely bypassing integrity checks. This allows it to deploy its payload undetected by traditional security solutions.
Encryption Mechanism
HybridPetya uses Salsa20 fast streaming synchronization as its encryption algorithm, which is used to encrypt important system files like the “\EFI\Microsoft\Boot\verify” file. The encryption is based on a key and nonce provided in the bootkit’s config. This configuration makes recovery efforts difficult for would-be victims looking to restore their systems.
As Martin Smolár, a cybersecurity expert, succinctly noted, for example, he noted that HybridPetya encrypts the Master File Table (MFT), which contains important metadata about files on NTFS-formatted volumes. This renders recovery extremely challenging without access to the correct decryption key.
“HybridPetya encrypts the Master File Table, which contains important metadata about all the files on NTFS-formatted partitions,” – Martin Smolár.
With danger thus completed, the bootkit’s encryption routine is done once the number of amino clusters decrypted reaches the value specified in the counter file. This mechanism plays a role in making sure that victims can’t just decrypt their files without going through the decryption procedure set by the ransomware.
“The decryption stops when the number of decrypted clusters is equal to the value from the counter file,” – Martin Smolár.
Countermeasures and Security Implications
The sudden appearance of HybridPetya underscores the need for clear cybersecurity procedures and particularly calls attention to the malevolent danger of UEFI malware. Judging by the analysis, experts agree that isolating UEFI malware from OS-level security protections is becoming ever more vital.
“Shade BIOS disassociate[s] UEFI malware from OS-level security,” – Matsuo.
At the same time, there’s an increased push for more robust security. To maximize their purpose of protecting against even the most sophisticated threats, these measures should target vulnerabilities at the root level. While traditional antivirus solutions might be inadequate to defend against moves such as HybridPetya, this highlights the need for smarter types of protection.