Format0 is the introduction to the string exploitation levels. There isn’t much to it except a bit of minutia in the printf function.
We must complete this level in under 10 bytes of input, which means we can’t do our typical print 1 billion As deal. What we instead do is use the width specifier of %s. We can do something like %64s to say we want a string of width 64, which sprintf will then print.
So our exploit simply looks like the following: