If you downloaded “CCleaner” software from antivirus company Avast between August 15 and September 12, you have a problem. Cisco’s Talos threat research group discovered that company’s software download page was compromised to host a malicious version of CCleaner that contains malware.
Computers that downloaded and ran that software became part of a botnet, a network of computers under the control of whomever is behind that malware.
Those that follow my advice to use the free OpenDNS service for their home networks are partially protected – your computer would still download and install the malware, but would be prevented from accessing the command and control servers the criminals use to deliver instructions to your computer.
If you use CCleaner, check your antivirus software to be sure it is completely up-to-date, and run a full system scan. Now that the malware is known, most commercial antivirus programs will begin to detect it (with varying degrees of success).
I have long recommended automatically updating software with the latest available patches and updates, as a core tenet of basic security for individuals and small businesses. After a Ukranian software company was hacked to deliver malware to taxpayers in that country, I wrote up an analysis of why I still held that recommendation.
I said then:
In over twenty years as a systems administrator and security professional – much of that time overseeing patching for a Fortune 100 company with a quarter million systems to update – I can count on one hand the number of catastrophic failures caused by patching, and still have fingers left over. Conversely, hardly a month goes by that I don’t see malware and criminals exploit vulnerabilities in Windows, browsers, office productivity software, mobile apps, building automation systems, industrial control systems, and other computing software.
It is becoming increasingly difficult to maintain that position… I suspect I am up to two hands now, but for the time being, I still find quickly updating is less risky than not patching.
Security for Real People