I also encountered this sort of problem in my old blogs WP 2.6 below. I haven’t updated my blog for so long. Hehe. Thanks for this now I know what’s that remv.php was.
I came to know about it after I downloaded all the files in my wp-content for back up purposes. My NOD32 suddenly quarantined and deleted it because it’s a virus.. woooot! I also tried to rename it and download it, but still, nod32 deleted it. I tried to view it in txt format and wooooot! It’s somekind of a weird hack, a loophole to access my humble blog.. whew.. that was scary. I just deleted it and upgraded to the latest version and now it’s fine. ??