Someone give this man an unusual Finder's Fee On Thu, Sep 3, 2015 at 3:59 PM, Refeek Yeglek <iamgoofb...@gmail.com> wrote:
> Hi, I'm one of the developers for Team Fortress 2 Classic, a source mod > project. Recently, someone abused a bug present in Source SDK 2013 MP to > distribute viruses to quite a few of our players and developers. The way > they did it was by abusing a spray exploit present in the SDK 2013 MP > edition to upload a file pretending to be a spray to all players and > executing it. The technical info on how it works from one of our other > coders will be posted at the end of this email, but here's what you need to > know as a server owner: > > We don't know how many source games are vulnerable. The big name VALVe > ones aren't, but any sourcemod probably is. This includes ones on steam > like Fortress Forever, or Fistful of Frags. > > If you're running a server for a non-VALVe or bigname(Titanfall, GMOD, > etc.) Source Engine game, then here's what you need to do: > > 1. Set sv_upload to 0 on your server. > > 2. If you are a TF2C server host, shut your server down and start scanning > your server for viruses. > > 3. Pester valve to fix this ASAP. > > TL;DR: > Sprays can be exploited to run code on people's systems and break into > accounts, we've had quite a few CS:GO and TF2 items lifted from accounts > and moved to trade alts and disappearing after that. Disable sprays ASAP if > you host a sourcemod multiplayer server. > > Here's the technical info for how stuff works: > > "The vulnerability is triggered by a missing check to see if a memory > allocation succeded in the loading of VTFs. When the material is loaded, > there is space allocated for the material. The crucial option in the using > of this exploit is the option to skip Mipmaps from the material. If, for > instance, the first mipmap is skipped, the game will copy the mipmap data > to buffer + size of first mipmap. When the memory allocation fails, the > buffer will be 0, because thats what malloc returns on out of memory. This > means, that the only factor determining where the block is put is > determined by the size of the first mipmap. This way you can put the data > in the second mipmap whereever you want, meaning you can write to a > predictable location in memory. This is additionally encouraged due to the > fact that ASLR is disabled for the module in question. From that point on > ROP is used to mark a controlled memory location executable and transfer > control to it, bypassing DEP. The distribution of the malicious material > file can be easily done through the use of the spray system, which uploads > a custom material to the server and distributes it. This is of course not > the only way to distribute it, but one used in this case. This is not > absolutely accurate and technical details have been left out due to them > not influencing this exploit." > > _______________________________________________ > To unsubscribe, edit your list preferences, or view the list archives, > please visit: > https://list.valvesoftware.com/cgi-bin/mailman/listinfo/hlds > >
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