Not a new problem
Back during the halcyon days of the internet, it wasn't uncommon for attackers to modify log files.
More recently, I worked for a manufacturer that was producing one of those toys that people were trampling fellow shoppers to get their hands on it. One of the assembly line drones hired to fill production gaps made his way into the factory mainframe. He patched the DB libraries so that finished products from his coworkers would be credited to him, earning him substantial performance bonuses. The data was also altered so that units built by him would appear as rejected by the inspector and thrown in the reject bin, but would really be going into his pocket, where he'd sell them for ~$500 a piece on eBay. The "rejected" units would be attributed to a random assembly drone and marked as being inspected by a random inspector.
All the production numbers, QA numbers, and inventory control would be in line with each other at the end of the day, so no one noticed. The guy ended up defrauding the company for close to $350,000 in bonuses and in proceeds from the stolen property. We only found out after attempting an upgrade to the db software and the diffs for the libraries wouldn't apply properly (since he messed with the lines being used to determine the proper context for line changes)