An anonymous reader shares a report: Hundreds of thousands of computers getting penetrated by a corrupted version of an ultra-common piece of security software was never going to end well. But now it's becoming clear exactly how bad the results of the recent CCleaner malware outbreak may be. Researchers now believe that the hackers behind it were bent not only on mass infections, but on targeted espionage that tried to gain access to the networks of at least 20 tech firms. Earlier this week, security firms Morphisec and Cisco revealed that CCleaner, a piece of security software distributed by Czech company Avast, had been hijacked by hackers and loaded with a backdoor that evaded the company's security checks. It wound up installed on more than 700,000 computers. On Wednesday, researchers at Cisco's Talos security division revealed that they've now analyzed the hackers' "command-and-control" server to which those malicious versions of CCleaner connected. On that server, they found evidence that the hackers had attempted to filter their collection of backdoored victim machines to find computers inside the networks of 20 tech firms, including Intel, Google, Microsoft, Akamai, Samsung, Sony, VMware, HTC, Linksys, D-Link and Cisco itself. In about half of those cases, says Talos research manager Craig Williams, the hackers successfully found a machine they'd compromised within the company's network, and used their backdoor to infect it with another piece of malware intended to serve as a deeper foothold, one that Cisco now believes was likely intended for industrial espionage.