The malware uses a hardcoded C2 server and a domain generating algorithm (DGA) as a backup, to send information about the affected system and fetch the final payload.
In a supply chain attack that may be unprecedented in the number of downloads, servers hosting CCleaner, a popular tool for cleaning up the PC, has been delivering a version of the said software with malware.
The trojan itself reportedly only ran on Windows 32 bit systems, but the values above were created on 64 bit systems as well. Malwarebytes will detect the presence of those values and flag them as These values are not created by any clean versions of CCleaner, just by the infected ones.
HKEY_LOCAL_MACHINE\SOFTWARE\Piriform\Agomo
Users that are unsure whether they were affected by this and whether their data may have been sent to the C2 server can check for the presence of the following values under the registry key: One point we should take note of is that the breach preceded the take-over of Piriform by Avast. Avast posted a clarification explaining what happened and giving a timeline of the events.