Please, I'm trying to understand second-preimage attacks on cryptographic hash functions. I understand the definition well: given a message and it's hash, an attacker finds another message which results in the same hash value. What I need is an explanation of a successful attack on a real hash function.
I have read lots of articles (from journals - especially Lecture Notes in Computer Science) on successful second-preimage attacks on some cryptographic hash functions but my mind can't get to grasp it properly.
Edit(1): Or, better still, can I have an explained example of a second preimage attack using the attack presented by F. Mendel et al. in the paper A (Second) Preimage Attack on the GOST Hash Function I'm desperately in need of some kind of simple step-by-step practical example of a successful attack.
Edit(2): Going back to the second preimage attack on MD4 based on the paper above, a working example is given (Table 2 on page 9 in the paper). I can leave out trying to understand the transformation from the target message M_0 to the weak message M, what I really need is some kind of step-by-step explanation of how the second-preimage M' was discovered using the method given. Please, I am new to cryptography, so an explanation of this example (or any other for that matter) is what can enable me understand this faster and better.
Thanks in advance.