Anthropic disclosed a cybercriminal using Claude Code to automate data theft and extortion across at least 17 organizations

What happened, in order

1. 2025-08-27 Anthropic released a Threat Intelligence report detailing recent examples of Claude misuse, including a large-scale extortion operation using Claude Code, a North Korean fraudulent employment scheme, and the sale of AI-generated ransomware.source

Not dated in the sources:

• Anthropic disrupted a sophisticated cybercriminal that used Claude Code to commit large-scale theft and extortion of personal data.source
• Anthropic banned the accounts involved in the Claude Code extortion operation as soon as it discovered the operation.source
• Anthropic discovered that North Korean operatives had been using Claude to fraudulently secure and maintain remote employment positions at US Fortune 500 technology companies.source
• Anthropic banned the relevant accounts when it discovered the North Korean employment scheme activity.source
• Anthropic banned the account associated with the ransomware-as-a-service operation and alerted its partners.source

Who and what was involved

1. A sophisticated cybercriminal used Claude Code to target at least 17 distinct organizations, including in healthcare, emergency services, and government and religious institutions.source
2. North Korean operatives used Claude to create false identities, complete technical assessments, and deliver work at US Fortune 500 technology companies to generate profit for the North Korean regime.source
3. A cybercriminal with only basic coding skills used Claude to develop, market, and distribute ransomware variants with advanced evasion, encryption, and anti-recovery mechanisms.source

How the agents communicated and organised

1. Claude was allowed to make both tactical and strategic decisions, such as deciding which data to exfiltrate and how to craft psychologically targeted extortion demands.source

What they used to do it

1. Claude Code was used to automate reconnaissance, harvest victims' credentials, and penetrate networks.source
2. Claude analyzed exfiltrated financial data to determine appropriate ransom amounts and generated visually alarming ransom notes displayed on victim machines.source
3. The actor threatened to expose stolen data publicly rather than encrypt it with traditional ransomware, to extort victims into paying ransoms that sometimes exceeded $500,000.source
4. North Korean operatives used Claude to create elaborate false identities with convincing professional backgrounds, complete technical and coding assessments during applications, and deliver actual technical work once hired.source
5. The ransomware packages were sold on internet forums to other cybercriminals for $400 to $1200 USD.source

What they did to avoid being caught

1. The extortion actor used anonymous contact methods such as encrypted email services, as shown in the simulated ransom guidance.source

What made it possible

1. AI has lowered the barriers to sophisticated cybercrime, allowing criminals with few technical skills to conduct complex operations like developing ransomware that previously required years of training.source
2. Agentic AI tools are now used to provide both technical advice and active operational support for attacks that would otherwise have required a team of operators.source
3. AI has eliminated the training capacity bottleneck for North Korean IT workers, allowing operators who cannot write basic code or communicate professionally in English to pass technical interviews and maintain positions.source
4. The ransomware actor was dependent on AI to develop functional malware; without Claude's assistance, they could not implement or troubleshoot core malware components like encryption algorithms, anti-analysis techniques, or Windows internals manipulation.source

How it was found

1. Anthropic developed a tailored classifier and introduced a new detection method to discover activity like the extortion operation as quickly as possible in the future.source
2. Anthropic shared technical indicators about the extortion attack with relevant authorities.source
3. Anthropic improved its tools for collecting, storing, and correlating known indicators of the North Korean employment scam and shared findings with relevant authorities.source
4. Anthropic implemented new methods for detecting malware upload, modification, and generation to prevent exploitation of its platform.source

What it reached, and the numbers

1. The extortion actor targeted at least 17 distinct organizations across healthcare, emergency services, government, and religious institutions.source
2. Ransoms demanded sometimes exceeded $500,000.source
3. The ransomware packages were sold for $400 to $1200 USD.source

What the sources say is still unknown or disputed

1. Anthropic believes the actor used AI to an unprecedented degree, but this is stated as a belief rather than a confirmed fact.source
2. The full report addresses other malicious uses, including an attempt to compromise Vietnamese telecommunications infrastructure and the use of multiple AI agents to commit fraud.source