Valve is no stranger to having its content prematurely exposed to the public. But the company just experienced the biggest asset leak in its existence, with multiple asset repositories for their games from 2016 washing up online. It's unclear if the leaker by the name of Leakerwanderer had a Source developer license, or how he got his hands on so much content from Portal, Counter-Strike: Source, Day of Defeat: Source, Half Life 2: Episodes & Multiplayer, and Team Fortress 2.
Valve is a globally renowned video game developer whose award-winning titles go through a long and arduos development process, resulting in hundreds of thousands of documents, photos, and animations necessary for production. These are stored in the form of asset repositories, which is typically how a game's files would be bundled-up to share with an external partner. It seems that someone with malicious intent had access to Valve's repository and made good bad use of it. With a limited number of Source developer licenses being granted finger pointing is already underway and this isn't the first time that Valve has had security issues.
The leaker used the popular gaming VOIP platform known as Discord to disseminate the materials through multiple outlets, most notably the Valve Cut Content Discord server. Here's what he had to say about the entire ordeal: I don't care anymore. I also did my toying around with it for a few years, did not upload because I was threatened every time [...] A real shame. I have no legal binding to these files. Not anymore. I have held onto these files since 2016. https://www.youtube.com/watch?v=8un3dBLVSCw