by bgsengine » Fri May 29, 2020 9:48 pm
Sounds like browser hijacking. It isn't uncommon to happen, may want to check your browsers for add-ons, recent updates, themes, etc that you may not have been aware of (or in some cases, they work fine for ages and suddenly cause problems, when a malware company buys the add-on and modifies it, then pushes an update) They easily bypass anti-virus because these are add-ons that you likely installed or activated yourself (even if you don't think you did, might have clicked something at some point in the distant past and installed it)
One nasty example I recall, was to do with AdBlock Plus - some enterprising malware company created an addon named AdblockPlus with a similar logo and gamed the ratings systems to get their addon to show up before the REAL (and safe) software - if you were unaware of it (and/or not paying close attention) when getting the addon on a new browser install, you ended up installing a browser hijacker that installed additional malware - I got bit by that myself some years back and had no end of trouble with it (despite having the best antivirus on the market with updated definitions, anti-virus does not necessarily prevent you from installing add-ons yourself... because the add-ons are NOT viruses.) I ended up having to completely reset and roll back the PC to factory fresh restore point in order to get rid of it finally, and then a fresh install of firefox and then some very careful reading of the add-ons when I went to re-install them..
How poor are they who have not patience. What wound did ever heal, but by degrees? - Iago (Othello Act II, Scene 3)