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Under the Surface of Azeroth:
A Network Baseline and Security Analysis
of Blizzard's World of Warcraft

Step 4: The Blizzard Updater
Once the patch file is completely downloaded, the Blizzard Updater automatically executes and applies the patch contents to the currently installed World of Warcraft client. At this point of the patch installation, there are a few things happening at the same time:

* The Blizzard Updater is actively patching the World of Warcraft client. The time to complete the patching is based on a number of variables, including the size of the patch and the processor speed of the local computer.

* Since many of the updates often take a minute or two, the Blizzard Updater displays the release notes for the patch. Some patches might include a one line description of the update and others may have pages of content. There's often some great information in the release notes, so don't miss the opportunity to familiarize yourself with the latest changes. If you want to revisit these in the future, you can visit Blizzard's web site at

* Even though the Blizzard Downloader has finished downloading the patch, it's still running behind the scenes to act as a "seed" for other swarm members. Although the Blizzard Downloader can be closed, it's considered polite to leave the Downloader running for as long as possible so that others can download the sections they need from your completed patch file.

Once the patching process is complete, the release notes and downloader continue to run on the desktop until closed with the "OK" button. Closing the Blizzard Updater will automatically close the Blizzard Downloader. With the World of Warcraft client downloaded and patched, the new client then launches and the startup processes begins anew.

If a World of Warcraft client is a few patch revisions behind, this upgrade process may need to occur many times before the World of Warcraft client is at the latest version. Blizzard's upgrade process is based on moving from one specific version to another specific version. The patches must be performed in order, and you can't move ahead to the next update unless the previous patch has been applied.

Isn't BitTorrent evil?
The BitTorrent protocol has only been around since 2001, but during this relatively short period of time it has managed to gain the interest of many organizations. Because of the distributed nature of BitTorrent and the ability to efficiently transfer a large amount of information, the pirate community now uses the BitTorrent protocol more than any other transmission mechanism. Transferring content via BitTorrent isn't illegal, but inappropriately copying copyrighted information is certainly against the law, regardless of the transmission medium. The BitTorrent protocol has undoubtedly received a negative reputation based on this illicit activity.

Fortunately, the BitTorrent protocol is also used for the good and righteous. Technologists all of the world use BitTorrent to share large distributions of the Linux operating system, and podcasters and artists such as Wil Wheaton ( have used BitTorrent to manage bandwidth and ensure availability of their latest offerings to the Internet community. Blizzard is certainly not alone in using the BitTorrent protocol to manage bandwidth, ensure availability, and speed the delivery of time-sensitive digital products to the end user.