The Twilight hack is the name given to the exploit found by Team Twiizers of Wiibrew.org in The Legend of Zelda: Twilight Princess

The Legend of Zelda: Twilight Princess

is an action-adventure game developed by Nintendo Entertainment Analysis and Development, and published by Nintendo for the GameCube and Wii video game consoles. It is the thirteenth installment in The Legend of Zelda series...

that permits homebrew

Homebrew (video games)

Homebrew is a term frequently applied to video games or other software produced by consumers to target proprietary hardware platforms not typically user-programmable or that use proprietary storage methods...

 developers and everyday users to run unofficial homebrew software from a Secure Digital card

Secure Digital card

Secure Digital is a non-volatile memory card format developed by the SD Card Association for use in portable devices. The SD technology is used by more than 400 brands across dozens of product categories and more than 8,000 models, and is considered the de-facto industry standard.Secure Digital...

 inserted into the slot on the front of the Wii

Wii

The Wii is a home video game console released by Nintendo on November 19, 2006. As a seventh-generation console, the Wii primarily competes with Microsoft's Xbox 360 and Sony's PlayStation 3. Nintendo states that its console targets a broader demographic than that of the two others...

. Notably, this is the first way found to boot homebrew software without the use of hardware modifications to the Wii console.

How it works

The hack exploits a buffer overflow

Buffer overflow

In computer security and programming, a buffer overflow, or buffer overrun, is an anomaly where a program, while writing data to a buffer, overruns the buffer's boundary and overwrites adjacent memory. This is a special case of violation of memory safety....

 error caused by loading a specially crafted save file for Twilight Princess. "Twilight Princess" save files store the name of the player's

Player character

A player character or playable character is a character in a video game or role playing game who is controlled or controllable by a player, and is typically a protagonist of the story told in the course of the game. A player character is a persona of the player who controls it. Player characters...

 horse in the game (originally "Epona"). The save file used by the hack presents a name much longer than expected to the Twilight Princess game. As a result, the excess characters in the horse's name overwrite a portion of the game's program in memory

Computer memory

In computing, memory refers to the physical devices used to store programs or data on a temporary or permanent basis for use in a computer or other digital electronic device. The term primary memory is used for the information in physical systems which are fast In computing, memory refers to the...

 with a special loader program. This causes the "Twilight Princess" program to crash as it runs the loader program. When the loader program runs, any program that is placed in the root directory

Root directory

In computer file systems, the root directory is the first or top-most directory in a hierarchy. It can be likened to the root of a tree — the starting point where all branches originate.-Metaphor:...

 of the SD card, with the filename

Filename

The filename is metadata about a file; a string used to uniquely identify a file stored on the file system. Different file systems impose different restrictions on length and allowed characters on filenames.A filename includes one or more of these components:...

 "boot.elf" or "boot.dol", will run.

What it was used for

Numerous applications have been written that can be run using this method. Since the hack loads an application through a glitch in Twilight Princess, in the past the game had to be loaded each time the user wished to run a homebrew application. This is no longer the case. Certain programs have been made to install custom Wii Menu channels such as the Homebrew Channel

Homebrew Channel

The Homebrew Channel is a freeware homebrew application loader that was developed to provide a way of easily running unofficial software on the Wii console. Once installed, it appears as a standard Wii Channel on the Wii Menu. When launched, it displays a list of applications found on an SD card or...

 so that the applications can be run from the Wii Menu instead of through the Twilight hack every time.

Nintendo's Response

On June 16, 2008, Nintendo released Wii Menu update 3.3 which automatically deletes and prevents the further storage of the unauthorized save files. However, within six hours of the update's release, community members found two bugs in the update that in conjunction can allow a slightly modified Twilight Hack to operate and have released a new version of the hack that will work on machines that have updated to 3.3.
A release for 3.4 firmware was later released for the general public to be able to run the Twilight Hack, even though each time the Wii boots it will delete the 'hacked' savefile from the system memory. However, this doesn't prevent users from copying the file from the SD card to the system memory back each time the Wii is turned on and running the exploit without restarting the system first.

System Menu 4.0 blocks any current version of the hack from being copied. Similar Smash Stack exploits exist in Super Smash Bros. Brawl

Super Smash Bros. Brawl

Super Smash Bros. Brawl, known in Japan as , often abbreviated as SSBB or simply as Brawl, is the third installment in the Super Smash Bros. series of crossover fighting games, developed by an ad hoc development team consisting of Sora, Game Arts and staff from other developers, and published by...

, Lego Indiana Jones: The Original Adventures

Lego Indiana Jones: The Original Adventures

Lego Indiana Jones: The Original Adventures is a 2008 video game developed by Traveller's Tales and published by LucasArts. The game allows players to recreate moments from the first three Indiana Jones films: Raiders of the Lost Ark, Indiana Jones and the Temple of Doom, and Indiana Jones and the...

, and Yu-Gi-Oh! 5D's: Wheelie Breakers that continue to work with all System Menu versions from 3.0 to 4.3, current as of December 13, 2010.