Wii system flaws

This page documents the various bugs in the Wii.

Hardware

Summary	Description	Successful exploitation result	Fixed in hardware revision	Discovered	Discovered by
HW_BOOT0 not clear-only	To prevent boot0 from being dumped, boot2 clears register HW_BOOT0 that allows the boot0 ROM to be read. However, Nintendo forgot to make this register clear-only, so simply re-enabling it allows boot0 to be dumped from 0xFFFE0000 or 0xFFFF0000 in memory.	boot0 can be obtained.	Unfixed	May 2008	fail0verflow
DVD-Video support is inadequately protected	While the Wii was initially meant to support DVD playback, it was scrapped to avoid needing to pay licensing fees. This support was removed in later revisions of the disc drive. However, when the Hollywood register ahbprot is disabled (e.g. by The Homebrew Channel), or diflags is enabled, homebrew can be used to read DVDs.	DVDs can be read on the Wii.	Unknown	July 2008	fail0verflow

boot1

Summary	Description	Successful exploitation result	Fixed in boot1 version	Discovered	Discovered by
strncmp used to compare hashes	boot1 verifies the signature of boot2 before booting it, however, the signing bug is present, allowing a fake boot2 to be loaded.	A custom bootloader can be installed, such as BootMii.	boot1c	Unknown	fail0verflow

boot2

Summary	Description	Successful exploitation result	Fixed in boot2 version	Discovered	Discovered by
No IOS signature check	Unlike boot1, boot2 does not check IOS's signature before launching it, allowing any System Menu IOS to be installed.	Any System Menu IOS can be installed.	Unfixed	Unknown	fail0verflow
No System Menu TMD signature check	When reading the System Menu TMD, no signature check is done; the IOS number is immediately trusted.	A custom System Menu IOS can be installed into a higher slot without overwriting the original IOS.	Unfixed	Unknown	fail0verflow

IOS

Summary	Description	Successful exploitation result	Fixed in system update	Discovered	Discovered by
Trucha bug	The Wii used the strncmp function to check signatures, which always stopped at the first null byte, weakening the security. More information can be found at signing bug.	Custom titles can be installed, and fakesigned discs can be played.	October 23 Update (still exploitable by IOS16 pirates), 4.0	Unknown	fail0verflow
STM release bug	The state transition manager checks if a handle is invalid before releasing it, but forgets to actually refuse to release it if it is invalid. More information can be seen at STM Release Exploit	Control over IOS can be gained.	4.0	Unknown	fail0verflow
No signature checks when switching IOS	IOS signatures are checked on install, but never on launch. This means that if an IOS can be installed, it can be launched without further exploitation.	Any cIOS that can bypass the installation signature checks can be launched.	Unfixed	July 2008	fail0verflow
No System Menu signature check	IOS does not verify the System Menu's signature before launching that, which means any System Menu can be installed.	A custom System Menu, such as Priiloader, can exist without bricking the system.	Unfixed	Unknown	crediar

System Menu

Summary	Description	Successful exploitation result	Fixed in system update	Discovered	Discovered by
No signature checks on NAND launch	Except when IOS is exploited, channels are checked for signatures before installation. However, no such check exists when launching from the NAND, allowing custom channels to live on the NAND perfectly fine. Launching from SD card is internally treated as copying a channel to the NAND before launching it, which is why signature checks exist for SD launching. Note that there is a check for discs, to prevent homebrew discs without any exploits.	If an unsigned channel can be installed to the NAND, it can be launched without further exploitation.	4.3-U (unfixed in 4.3-Mini)	Unknown	fail0verflow

MIOS

Summary	Description	Successful exploitation result	Fixed in MIOS version	Discovered	Discovered by
Memory not cleared before booting GC game	When MIOS loads a GameCube game, it never clears the 48K bytes of memory that the game should not have access to. By using a pair of tweezers to change the address lines, the entire memory can be dumped.	MIOS and the rest of memory can be dumped using GameCube homebrew.	v8	Unknown	fail0verflow

Nintendo SDK

These flaws exist in every official application, because they are bundled in, probably in the official SDK. For this reason, they are very difficult to fix.

Summary	Description	Successful exploitation result	Fixed in	Discovered	Discovered by
No upper bound to CCB array	The Fluoride Bluetooth stack includes a function to get a CCB from an ID. This function checks whether the ID is below the lower bound, however, no upper bound is enforced. By carefully crafting an ID, a fake CCB entry can be placed in the handles array. Sending a packet to free this struct causes it to "unlink" from its adjacent entries, which can be used to get an arbitrary write, and therefore code execution.	PPC code execution (used in Bluebomb)	vWii	September 2019	Fullmetal5