A friend of mine recently bought a used Wii with the Homebrew Channel installed on it but he wasn't sure if there was still any IOS on it that accepts faked signatures.
He tried some other tool he found on the wiibrew wiki but it crashed while it was trying a very early IOS version that is now replaced with a small stub that apparently cannot do anything.
I therefore decided to write my own small tool which gets the list of installed IOS versions, tries to detect if they actually work and then checks if they are sill vulnerable.
It also checks if you can still call ES_DiVerify (aka ES_Identify) from the powerpc to make IOS think that you actually are a different title. This function is normally only used by the DI driver to check the game's signature and switch to its identity. IOS did not check the caller of the function which essentially allowed you - given that you had a 'valid' tmd/tik - to switch to any titles identity. This was also fixed in the latest update.
Well, maybe someone else might also find this helpful. The binary can be found on the wiibrew wiki page i created and the source is in a git repository...