I have downloaded the core wordpress files and copied them over the existing ones, hoping that would fix the problem, but it hasn't.
Can anyone provide advice that might help clean up these infections but still leave the sites functional? Having to start 5 wordpress sites from scratch (with all their individual customisations) would be such a chore.
I will provide an example site, but just to repeat: this site has been infected!
http://www.nalastud.co.nz/ Watch the taskbar while it loads and you'll see what I mean.
Any tips please?