Making Finfisher Malware Undetectable
lqdc.github.io
lqdc.github.io
You can almost try this 'at home' - upload a file to VirusTotal and try to get it to match two or three AV's detections. It will then be flagged by at least ten AVs next week. This is because VirusTotal shares all uploaded files with antivirus products.
Another example: This one marked by 2 AVs (malwarebytes and Bkav) in September. A month later it was only marked by 3. https://www.virustotal.com/en/file/e5712fc604d6285038c6a7fe2...
Far-fetched but not impossible. I wish I could remember the source.