To recap, on September 18, 2017, we disclosed that CCleaner had been targeted by cybercriminals, in order to distribute malware via the CCleaner installation file. The altered installation file was downloaded by 2.27 million CCleaner customers worldwide. The malware was introduced to the build server of Piriform, the company developing CCleaner, some time between March 11 and July 4, 2017, prior to Avast’s acquisition of Piriform on July 18, 2017