The game's audio was well received, particularly the background music. By assigning music to different areas of the game world, reviewers felt that the fantasy style added to the player's immersion, and that the replay value was increased. The sounds and voices used by characters and NPCs, as well as the overall sound effects, were felt to add a "personality" to the game.
When players create World of Warcraft accounts, they are asked to choose a username and password. Afterward, whenever they play World of Warcraft, they are asked to supply the same username and password in full. This is also the case when using account management facilities online. This type of authentication is vulnerable to keystroke logging. While this is not unique to World of Warcraft and is common to many MMORPGs, the game has been directly targeted with trojans being specifically crafted to capture account login details. Attacks have been reported as early as May 2006 and may extend as far back as July 30, 2005. The game does, however, allow players to save their account name to the program to allow the player to only have to type their password.
The Corrupted Blood plague incident was one of the first events to affect entire servers. Patch 1.7 saw the opening of Zul'Gurub, the game's first 20-player raid dungeon where players faced off against a tribe of trolls. Upon engaging the final boss, players were stricken by a debuff called "Corrupted Blood" which would periodically sap their life. The disease was passed on to other players simply by being near infected players. Originally this malady was confined within the Zul'Gurub instance, but it made its way into the outside world by way of hunter pets or warlock minions that contracted the disease.