Hacker Uses AI Agents to Breach Over 100 Websites

A cybersecurity researcher has documented a case in which a hacker used artificial intelligence agents to autonomously break into websites belonging to more than 100 companies. The incidents, observed over the past couple of weeks, involved targets such as farm equipment maker Deere, home appliance company SharkNinja, and engine manufacturer Cummins.

According to Snorre Fagerland, principal threat researcher at cybersecurity company NorForge, the hacker outsourced the majority of the work to AI. Fagerland discovered the activity while scanning for inadvertently exposed instances of Cairn, an open-source AI problem-solving platform. Beginning around Oct. 2, he identified about two dozen instances of Cairn being used for malicious purposes, allowing him to observe the cybercriminals' activities in real time.

Autonomous Intrusion Tactics

The hacker, described as Chinese-speaking, issued terse instructions to the AI agents, outlining intrusion tactics in fewer than 100 Chinese characters. Starting on September 25, the agents targeted e-commerce websites in the United States, Canada, Australia, and Japan. By late last week, the agents had attempted to breach more than 1,200 sites.

Fagerland estimated that successful intrusions typically required around 23 hours of autonomous probing for vulnerabilities. The campaign appeared to utilize a mixture of China’s DeepSeek and Anthropic’s Claude Code. The total cost of the operation was approximately US$5,000 in tokens, or about US$50 per successful hack.

In one instance, after failing to find weaknesses in a public-facing application, the AI agents searched digital records to locate associated infrastructure. They identified a public-facing control panel, found a subtle data processing weakness, and leveraged it to trick the server into executing malicious commands.

"It’s not straightforward to come up with solutions like that," Fagerland said. "It’s not script kiddie stuff."

Corporate Responses

Reuters was able to identify several victims by reviewing the hacker’s Cairn activity. Deere stated that it had taken "necessary remediation actions" and had "no indication that sensitive information was accessed." SharkNinja reported that the hack affected a standalone site containing only product support information and that the threat had been contained. Cummins said it was "investigating the report of a potential cyber-attack on a website operated by one of our third-party vendors."

Two smaller businesses also acknowledged being compromised, while other victims listed in the data did not respond to inquiries. Reuters could not determine the extent of any unauthorized data extraction.

Broader Implications for AI Security

The incident highlights growing concerns regarding the capability of commercially available AI agents to conduct complex cyberattacks without human supervision. Fagerland noted that his findings provide real-life evidence that AI can perform intrusions from start to finish, significantly amplifying the power of a single malicious actor.

"It’s a new world now," said Fagerland.

This event follows other reports of AI misuse in the cybercriminal underground. In August, Israeli firm Gambit Security found that Russian-speaking extortionists used SpaceX’s Cursor AI tool to breach seven organizations. In September, Gambit documented an AI-driven spree that breached 25 companies and stole at least 600,000 credit card records. Additionally, cyber intelligence company Bitsight reported last week that discussions on using autonomous agents were surging in cybercriminal forums.

The author of Cairn, whose social media handle is "le1xia0," acknowledged receiving a message from Reuters but did not immediately answer questions. In a recent post on X, the author stated that the platform was "an innovative type of multi-agent architecture and was not designed for hacking attacks. If it is used to carry out harmful hacking attacks, that is not my intention."

Why it matters

This case demonstrates that autonomous AI agents can now execute sophisticated cyberattacks with minimal human input, lowering the barrier for large-scale breaches. The low cost and high efficiency of these attacks, combined with the ability to operate without supervision, pose significant challenges for traditional cybersecurity defenses and highlight the urgent need for new security frameworks tailored to agentic AI systems.

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Sources

• ctvnews.ca: How one hacker broke into more than 100 company websites using AI
• bnnbloomberg.ca: How one hacker broke into more than 100 company websites using AI
• theverge.com: A hacker broke into John Deere and SharkNinja with an army of AI agents | The Verge

This article was drafted with AI assistance and checked against the sources above. Company claims are reported as claims. Cover image is AI-generated.