Possibly also to be used as communication encryption key” in the registration key. Piriform's investigation found the malware was stashed in the app's initialisation code that is usually installed during compilation and stashed information, such as, “randomly generated number identifying a particular system. “We would like to apologise for a security incident that we have recently found in CCleaner version and CCleaner Cloud version ,” Yung said, adding, “the threat has now been resolved in the sense that the rogue server is down, other potential servers are out of the control of the attacker, and we're moving all existing CCleaner v users to the latest version. An as-yet-unknown party inserted a two-stage backdoor capable of remote code execution.ĬCleaner has been downloaded more than 2 billion times, according to a November 2016 press release, and the company is recommending all its users update to the latest version 5.34. Piriform vice president Paul Yung said the issued was first noticed on 12 September when an unknown IP address began receiving data in version of CCleaner, and CCleaner Cloud version, on 32-bit Windows systems.įurther research discovered that these versions of the app had been illegally modified before being released to the public.

The free computer maintenance app CCleaner, distributed by Avast, maybe have exposed more than two million computers to a multistage malware payload.Ĭisco's Talos threat intelligence group believes the malware was most likely added by an outside actor, but the researchers did not rule out the possibility that the manoeuvre was an inside job. Avast acquired Piriform in July and folded the company into Avast's consumer business unit and retained the CCleaner brand.

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