Malicious code has been discovered in two versions of Piniform's CCleaner housekeeping utility, the company disclosed on Monday. Piniform is owned by Avast, whose security products are used by more than 400 million people. The malware infecting CCleaner could give hackers control over the devices of more than 2 million users. CCleaner is designed to rid computers and mobile phones of junk, such as unwanted applications and advertising cookies. Two versions of the program were modified illegally before they were released to the public.