Microsoft has confirmed that two devices on its corporate network were compromised to help a notorious gang of Russian criminals push Viagra, Human Growth Hormone, and other knockoff pharmaceuticals.

The admission came in response to an article The Register published on Tuesday. It reported that two internet addresses belonging to Microsoft were helping to route traffic to more than 1,000 websites that belong to a fraudulent online pharmacy known as the Canadian Health&Care Mall. Microsoft on Wednesday said an investigation of that report confirmed the hijacking was the result of an attack on machines connected to its network.

“We have completed our investigation and found that two misconfigured network hardware devices in a testing lab were compromised due to human error,” the five-sentence statement said. “Those devices have been removed and we can confirm that no customer data was compromised and no production systems were affected. We are taking steps to better ensure that testing lab hardware devices that are internet accessible are configured with proper security controls.”

According to network security researcher Ronald F. Guilmette, the Microsoft IP addresses had been used to host the websites' authoritative name servers since at least September 22. El Reg ran the data he supplied by experts in DNS and botnet take-downs, and most said it likely indicated that one or more machines on Microsoft's network had been infected with malware.

About 24 hours after The Reg article ran, security reporter Brian Krebs reported that one of the two Microsoft IPs had been used to coordinate a massive denial-of-service attack against his website, KrebsOnSecurity.com. Shortly after the attacks began on September 23, researchers were able to pinpoint the Microsoft IP and within hours they notified Microsoft of the compromised IPs, the site reported.

Remarkably, the machines weren't unplugged from Microsoft's network until Tuesday, almost three weeks later, shortly after The Register article was published. Also notable, according to Krebs, the machines that were compromised were running Linux. ®