Security researchers have just identified what could be the first ‘AI-powered’ ransomware strain – and it uses OpenAI’s gpt-oss-20b model

AI ransomware and cyber crime concept image showing a digitized human eye observing networks with computer code.

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Researchers at cybersecurity firm ESET have discovered what they said is the "first known AI-powered ransomware" strain.

Dubbed ‘PromptLock’, researchers said it uses OpenAI's open source gpt-oss:20b model, released earlier this month, locally via the Ollama API to generate malicious Lua scripts on the fly, which it then executes.

"PromptLock leverages Lua scripts generated from hard-coded prompts to enumerate the local filesystem, inspect target files, exfiltrate selected data, and perform encryption," said researchers Anton Cherepanov and Peter Strycek in posts on several social media sites, including X.

"These Lua scripts are cross-platform compatible, functioning on Windows, Linux, and macOS. Based on the detected user files, the malware may exfiltrate data, encrypt it, or potentially destroy it."

PromptLock is written in Golang and uses the SPECK 128-bit encryption algorithm, developed by the US National Security Agency (NSA), to encrypt files. It sends its requests through Ollama, an open source API for interfacing with large language models.

The Bitcoin address used in the AI prompt for a payment demand is the one associated with the cryptocurrency's creator, Satoshi Nakamoto, whose real identity has never been discovered.

Cherepanov and Strycek said they've identified both Windows and Linux variants uploaded to VirusTotal, a Google-owned service that catalogs malware and checks files for malicious threats.

The good news is that the malware doesn't seem to be fully functional yet - the destruction functionality hasn't been implemented.

"Although multiple indicators suggest the sample is a proof-of-concept (PoC) or work-in-progress rather than fully operational malware deployed in the wild, we believe it is our responsibility to inform the cybersecurity community about such developments," Cherepanov and Strycek said.

Concerns rising over AI ransomware threats

Ransomware gangs have increasingly been using AI to automate communications and enhance their social engineering techniques, research shows.

A recent study from Acronis found that the increase in the use of AI by ransomware gangs appeared to be reflected in their chosen threat vectors. Social engineering and BEC attacks increased from 20% to 25.6% in the first five months of 2025 compared to the same period in 2024.

This, researchers noted, was probably down to the growth in AI use for crafting convincing impersonations.

Earlier this year, Malwarebytes warned that businesses need to be prepared for AI-powered ransomware attacks.

Up to now, AI agents have generally been used to increase the efficiency of attacks, rather than introducing new capabilities or altering the underlying tactics used by hackers.

According to Malwarebytes, though, this could all change soon as attackers use AI more broadly.

"We are in the earliest days of regular threat actors leveraging local/private AI, said John Scott-Railton, a spyware researcher at Citizen Lab, commenting on the ESET research. "And we are unprepared."

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Emma Woollacott is a freelance journalist writing for publications including the BBC, Private Eye, Forbes, Raconteur and specialist technology titles.