Cryptanalysis

Pretty stuck on this one. I noticed a few odd things about the binary:

1. The length is NOT a multiple of 16 bytes (the block size of AES). This made me thing that maybe part of the ciphertext is a 192-bit key.
2. There is a weird pattern in the ciphertext: one instance of 00 00 00 00, two instances of 10 00 00 00, and one instance 20 00 00 00.

Ive tried using part of the ciphertext as the key, but have had no success so far. Am I at least on the right path or am I stuck in the wrong direction?

You are on the right path. You should think why this file has such a pattern, or actually a "format". Google might help you on that