Blizzard Entertainment Uses Spyware to Verify EULA Compliance


I recently performed a rather long reversing session on a piece of software written by Blizzard Entertainment, yes — the ones who made Warcraft, and World of Warcraft (which has 4.5 million+ players now, apparently). This software is known as the ‘warden client’ — its written like shellcode in that it’s position independent. It is downloaded on the fly from Blizzard’s servers, and it runs about every 15 seconds. It is one of the most interesting pieces of spyware to date, because it is designed only to verify compliance with a EULA/TOS. Here is what it does, about every 15 seconds, to about 4.5 million people (500,000 of which are logged on at any given time):

The warden dumps all the DLL’s using a ToolHelp API call. It reads information from every DLL loaded in the ‘world of warcraft’ executable process space. No big deal.

The warden then uses the GetWindowTextA function to read the window text in the titlebar of every window. These are windows that are not in the WoW process, but any program running on your computer. Now a Big Deal.

I watched the warden sniff down the email addresses of people I was communicating with on MSN, the URL of several websites that I had open at the time, and the names of all my running programs, including those that were minimized or in the toolbar. These strings can easily contain social security numbers or credit card numbers, for example, if I have Microsoft Excel or Quickbooks open w/ my personal finances at the time.

Once these strings are obtained, they are passed through a hashing function and compared against a list of ‘banning hashes’ — if you match something in their list, I suspect you will get banned. …

Next, warden opens every process running on your computer. … I watched warden open my email program, and even my PGP key manager. Again, I feel this is a fairly severe violation of privacy, but what can you do? It would be very easy to devise a test where the warden clearly reads confidential or personal information without regard.

This behavior places the warden client squarely in the category of spyware. What is interesting about this is that it might be the first use of spyware to verify compliance with a EULA. I cannot imagine that such practices will be legal in the future, but right now in terms of law, this is the wild wild west. You can’t blame Blizz for trying, as well as any other company, but this practice will have to stop if we have any hope of privacy. Agree w/ botting or game cheaters or not, this is a much larger issue called ‘privacy’ and Blizz has no right to be opening my excel or PGP programs, for whatever reason.

EDITED TO ADD: Blizzard responds. See also here. Several commenters say that this is no big deal. I think that a program that does all of this without the knowledge or consent of the user is a big deal. This is a program designed to spy on the user and report back to Blizzard. It’s pretty benign, but the next company who does this may be less so. It definitely counts as spyware.

EDITED TO ADD: This is a great post by EFF on the topic.

EDITED TO ADD: BBC has an article on the topic.

Posted on October 13, 2005 at 2:11 PM

Sidebar photo of Bruce Schneier by Joe MacInnis.