OK I just did this just this very minute having just binned yet another large protected RAR file, no i am not filling in your f*cking surveys FFS!! I undeleted it and tried again, search the interweb and ... no I am not downloading tools that are fake or on trial and do nothing unless the password is 3 letters long. So then...find the temp folder where it is extracted to, usually windows temp folder at user/appdata/local/temp (if cluttered delete the excess so you can find the folder created during extraction... If you open it in winrar and enter wrong password the temp extraction folder disappears as soon as it reaches 100% Bollocks... I was going to change the temp folder to a newly formatted drive and then do data recovery on it as soon as winrar deleted it, but here's the very very very easy solution: If you use 7 zip the temp folder does NOT get deleted until you click close! Simply let it extract with wrong password, do NOT click Close, find the temp folder it extracted to and then copy the files out to where you want them. Job done. No password cracking needed.
Bollocks again, I spoke too soon LOL as the ISO was not valid and not openable or mountable. Will try again on another. Edit: sorry should have tested this before posting but having managed to extract the ISO it didnt occur to me me it would be an empty shell.
