Thousands of Android devices come with unkillable backdoor preinstalledArs TechnicaSomehow, advanced Triada malware was added to devices before reaching resellers.

Human Security researchers found seven Android TV boxes and one tablet with the backdoors installed, and they’ve seen signs of 200 different models of Android devices that may be impacted, according to a report shared exclusively with WIRED. The devices are in homes, businesses, and schools across the US. Meanwhile, Human Security says it has also taken down advertising fraud linked to the scheme, which likely helped pay for the operation.

“They’re like a Swiss Army knife of doing bad things on the Internet,” says Gavin Reid, the CISO at Human Security who leads the company’s Satori Threat Intelligence and Research team. “This is a truly distributed way of doing fraud.” Reid says the company has shared details of facilities where the devices may have been manufactured with law enforcement agencies.