Powerful new AI models are powering a growing wave of cyber attacks, experts say

Starting on Sept.

25, a hacker set loose an army of AI agents that attempted to break into over 1,200 websites over the next few weeks—autonomously, with no additional work required of the human hacker after sending them off on their task.

The agents successfully breached about 100 companies, including farm equipment maker Deere , home appliance ​company SharkNinja, and engine manufacturer Cummins, according to Reuters, which first reported the incident, discovered by cybersecurity researchers.

While the hacker didn’t need to execute the attack themselves, they had to foot the bill for the AI tools.

It cost about $5,000 worth of tokens from a combination of DeepSeek and Anthropic’s Claude Code models, researchers told Reuters.

That’s roughly $50 per successful breach.

Autonomous attacks powered by AI agents are becoming more common, Jessica Ji, a senior research analyst at Georgetown’s Center for Security and Emerging Technology (CSET) told Fortune .

This is primarily happening because the tools have “gotten meaningfully better” over the past year or so, she said.

Specifically, AI companies have improved their models’ coding skills, which has led to “dramatic increase in their ability to do cybersecurity-relevant tasks like analyze large volumes of code,” she said.

Also, they have become more agentic, meaning they can use other software to complete tasks, as opposed to merely outputting text.

“These AI systems are now both more capable of hacking and are able to act more autonomously,” Ji said.

Agents powered by large language models (LLMs) can run all day and night without stopping, at a “fraction of the cost of human attackers,” Varun Chandrasekaran, Assistant Professor of Electrical and Computer Engineering at the University of Illinois’ Grainger College of Engineering, told Fortune .

This “fundamentally changes the economics of exploitation,” he said, citing the attackers who spent only $50 per successful reach.

Debate grows over the value and risks of open weight AI Open-weight models, or those that are publicly downloadable and customizable, can also offer powerful, low-cost tools for agentic hacks, Ji said.