False positive. File is clean. Every trainer is unique and has a unique signature to it. We have no control over which trainers various AV products decide to mark as malware. Add an exclusion list for your CH trainers folder to prevent the trainers from being blocked or falsely detected.
More information would be helpful, too.
If your security software is Bitdefender most probably it got updated to the 2018 version. It now has the 'Advance Threat Defense' module activated (which was disabled by default in the 2017 version). You need to disable this module completely while using the trainer, even though you have exclusions in place.
Bitdefender (I assume) will now tell that you're vulnerable. You may send the trainer for further examination to Bitdefender.
I am using BitDefender, and I notice that "Threat Defense" module was active, and was the cause of my problems with this trainer. Once I disabled it, it worked normally.
Thank you again.