fogbank said:BenJeremy said:CIO36 is IOS249? Are they patches or extensions? What is the difference between a fakesign exploit and a banner exploit - i.e. why is the CIOS the most important thing?
Great questions. I'll take a stab:
CIOS36 is not really IOS249 per se. The Wii has IOS "slots" in which IOS'es can be installed. They are numbered from 0 to 254. Only the lower slots (61 and below) are currently used by legitimate Wii IOS'es. The rest are unused.
cIOS36 is a customized version of the legitimate Wii IOS version 36. Technically it could be installed into any unusued IOS slot, but it is most commonly installed into slot # 249. That then becomes IOS249.
The fakesign exploit came about when it was discovered that the Wii developers used a flawed version of the C string compare function (strncmp) to check the validity of content signatures. The function would check each character of the signature string until it reached the end of the string or until it reached a null byte. I think the issue here is that it did not check the length of the signature string to begin with. If you create a signature string with a null byte early in the string, the mathematical odds of it being seen as valid are much greater, since there are far fewer characters to compare (the strncmp function stops at the first null byte).
START SPECULATION
The banner exploit is new to the Wii and has not been publicly released yet. In general a banner exploit would be similar to other exploits on other systems where there is a flaw in processing graphic images (think TIFF exploit on PSP, BMP or PNG exploits on Windows, etc...). The exploit would likely involve an unchecked buffer and employ a stack or heap corruption method.
END SPECULATION
cIOS is important to softmodders because later versions included code to access DVD content from the Wii's optical drive. This allows the cIOS to be used to read burned games as DVD's. Additional PPC code (i.e. a "loader") is then used to tell the system to load the game from the DVD.
Whew...
Most of this I believe to be accurate, but there are always those who know it better
Thanks for taking a stab at these.
I hope this guide gets linked in the pinned "useful guides" topic.