I believe there is certain criteria for the Avast offer to show like if there is no AV currently installed on the system/paid AV expired etc.
Certainly possible, but doesn't explain the different installers.
The one on piriform as of 5mins ago: ccsetup536.exe (10,183 KB)
The one I have (which I think I got from piriform yesterday): cc_setup536 (10,546 KB)
You can check the validity of your download at: https://forum.piriform.com/topic/49067-ccleaner-v536/?do=findComment&comment=287835
I've already addressed your concerns that this doesn't shoe your question about a cc_setup536 file nor the install of Avast.
Once I know, you'll know.
The comment comes from the Desktop Project Manager of Ccleaner:
"The user has been included in a test group where Avast Antivirus is offered during the installation. If they wish to verify the installer hash for authenticity they should refer to this list:
https://forum.piriform.com/topic/49067-ccleaner-v536/?do=findComment&comment=287835"
