Hacker used autonomous AI agents costing about $5,000 to breach 100+ companies, researcher says

A Chinese-speaking hacker broke into websites of more than 100 companies — including farm equipment maker Deere, home appliance company SharkNinja and engine maker Cummins — while doing almost none of the work. They outsourced the spree almost entirely to artificial intelligence, according to Snorre Fagerland, principal threat researcher at cybersecurity company NorForge.

In a report provided to Reuters ahead of publication on Monday, Fagerland said he had discovered the hacker while scanning the web for inadvertently exposed instances of Cairn, an open-source AI problem-solving platform popular with hackers. Beginning around October 2, he found about two dozen malicious Cairn instances.

The hacker began on September 25, setting AI agents loose against e-commerce websites in the US, Canada, Australia and Japan. The agents attempted to break into more than 1,200 sites; successful intrusions typically took around 23 hours of autonomous probing. Fagerland estimated the campaign — which appeared to use a mixture of China’s DeepSeek and Anthropic’s Claude Code — consumed roughly $5,000 in tokens, about $50 per successful hack.

“It’s a new world now,” Fagerland said, calling his findings real-life evidence that commercially available AI agents can pull off complex intrusions from start to finish without human intervention. Reuters verified the victims by reviewing the hacker’s Cairn activity, though it could not ascertain how far breaches led to data extraction. Separately, India’s CERT-In issued an October 15 advisory on autonomous AI agents that accessed live systems of Indian organisations through basic cyber-hygiene lapses, The Hindu BusinessLine reported.