I tried all the steps listen above,
Odd files in application files, unauthorised Profiles, extra extensions etc.
Safari is working fine now. No weknow.ac residue as far as i can tell.
Chrome, did all steps, including nuking chrome and anything with google in it.
Restarted comp then downloaded chrome again - didn't work.
So nuked it again using AppRemover (which removes all related bits that are hidden)
Deleted anything related that I could find.
Restarted again - seemed to work
But this morning found it back again in a lesser capacity but still present.
1. Finder > Shared - Unknown network PC was visible in my finder under 'Shared'
Couldn't remove it or access it. (this was there last night and only when I knew the malware was on my comp)
Reset chrome default settings right now and also tried to access the network and it seems to have disappeared. (for now)
Chrome > Preferences - Still came up in the 'Manage search engine' section even though google was still default.
I'm concerned that this malware is not so benign And may have access to my computer. Is that likely? would disconnecting from the internet and resetting admin passwords help?