Stolen LLM access leaves companies with soaring cloud bills

Criminals hijacking corporate LLM services are generating fraudulent charges exceeding $100,000 a day, according to Google’s Mandiant incident responders. Some organizations accumulated $1 million in charges before revoking intruders’ access. Known as LLMJacking, the practice uses stolen credentials to consume expensive computing resources and AI services at victims’ expense.

In a case involving the group Google tracks as UNC6993, attackers obtained LLM API keys, generated additional keys and enabled services within a victim’s cloud projects, accumulating $100,000 in charges. Another intruder selected premium models and repeatedly created and deleted service accounts to bypass rate limits while monitoring billing.

Google also observed more than 500,000 LLM API calls in less than eight hours using stolen third-party keys to power the token-routing service Jet Night. Google believes the service relies on stolen credentials to sustain its unusually low prices. Investigators have identified a division between criminals who establish access and operators managing downstream monetization infrastructure, called LLM Mixers.

Attackers also use session-hijacking pages that persuade users to surrender active access tokens, bypassing passwords and multifactor authentication. Google recommends stronger identity and access management, supply chain security, centralized secrets management, key rotation, least-privilege permissions and automated scanning to remove exposed credentials from source code.