[cnorthwood]

Early in my career I was working for a well-known anti-virus firm. They had a crash of their Perforce servers and it turns out the backups were not good and the most recent good one was several months old. They painstakingly restored it from the good backup and forensic recovery of the drives, but there were several files that were still missing to fully restore the archive. They did know the hashes of the files, so what they did was push out a bunch of custom virus signatures to the dogfooding (internal testing) environment which flagged any files with those hashes as viruses, and then asked anyone who had a hit to send the file into central IT to get it resolved. It was fairly clever I thought!