In order to help we need information and we/I can't talk about other antiviruses only if it is specific to Avast. I have no idea what YARA rules or signatures are about.
If you are getting an Avast Alert what is the information contained in that alert. You can attach a screenshot of the Alert window with the Details option selected.
Attaching Images to your post - When you Click the Reply button it opens a text window for you to post your comment (reply or post).
Click the Preview button, that shows what you have input and expands it to include 'Attachments and other options'. Click that it further expands, here you can attach images, etc. at the bottom of your post.
See my attached image, click to expand.