Google and several partners have shut down a botnet in more than 1.3 million TV set-top boxes, CyberScoop reports. Google says an approved Android device maker built it on purpose. Google announced the action on Monday.

Google alleges that Videostrong Technology Co. put a backdoor into devices it sold, the Verge reports. The company is based in Shenzhen, China. Google says it has dismantled the backdoor and "cut ties" with the company, the Verge says.

"We assess with high confidence that the backdoor and botnet were intentionally developed, deployed, and operated for financial gain by Videostrong Technology Co.," Google's Threat Intelligence Group said in a report, according to BleepingComputer.

Google says Videostrong sold access to the infected devices to criminal affiliates, CyberScoop reports. The devices were used for ad fraud, data theft and routing malicious traffic, without their owners knowing.

The bad code loaded after a device was first switched on, CyberScoop reports. That helped it slip past Google's tests. Most infected devices were TV boxes, the Verge reports. Karaoke machines, telehealth devices and digital signs were also hit.

Google says it also took down control servers used by more than a dozen related malware families, BleepingComputer reports. That cut off access to at least 10 million more compromised devices, Google says. Google says not all of those are Android devices, BleepingComputer reports.

The botnet spanned more than 170 countries, according to researchers at TrendAI, CyberScoop reports. Nearly 44,000 infected devices were in the United States between June and October, CyberScoop says.

Google has banned Videostrong and any future offshoots from making or selling certified Android devices, the Verge reports. Google says it also changed its review process for device makers, the Verge reports.

The cited outlets do not include a response from Videostrong.