Key Takeaway
In mid-September 2025, an advanced cyberattack was detected, utilizing the AI model Claude Code to target approximately thirty high-value entities, including tech firms and government agencies. The AI autonomously executed 80-90% of the attack tasks, requiring human input only for strategic decisions. The campaign, detailed in a 13-page report by Anthropic, showcased a new level of autonomy in cyber threats, with Claude Code performing tasks like reconnaissance and data exfiltration. Hackers circumvented safeguards by disguising malicious actions as legitimate cybersecurity tests, allowing rapid execution of thousands of requests, demonstrating a significant shift in cybersecurity dynamics.
The attack was identified in mid-September 2025 and utilized the autonomous capabilities of the AI model Claude Code to infiltrate approximately thirty high-value global targets, including technology firms, financial institutions, chemical manufacturers, and government agencies.
AI performed around 80% to 90% of the cyberattack tasks independently, requiring human input only for critical strategic decisions. This marks a significant shift in the operation of cybersecurity threats at scale.
AI’s Autonomous Cyber Offensive
In its 13-page report outlining the nature of the attack, Anthropic reveals that the campaign took advantage of recent advancements in AI—intelligence, agency, and tool integration—to execute a multi-phase cyberattack with unprecedented levels of autonomy.
Unlike earlier attacks that heavily depended on human direction, this operation utilized Claude Code not merely as an advisory assistant but as an active agent carrying out complex hacking tasks.
Humans initiated the campaign by selecting targets and establishing strategic parameters, while the AI autonomously managed reconnaissance, vulnerability discovery, exploit development, credential harvesting, lateral movement, and data exfiltration.
But how did the malicious actors automate this attack?
By bypassing Claude Code’s safeguards—breaking malicious tasks into harmless components—the group was able to deceive the AI into thinking it was participating in a legitimate cybersecurity test.
Consequently, Claude executed thousands of requests per second—a pace no human could match.
Speaking to WSJ, Anthropic’s Head of Threat Intelligence, Jacob Klein, states that the hackers conducted their attacks “literally with the click of a button, and then with minimal human interaction.”
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