Known plaintext, unknown 128 bit block cipher I have an encrypted configuration file from an embedded device which I'm trying to decrypt. The file seems to be encrypted in 128bit blocks, as changing a single option causes a 16 byte block to change (all bytes change). The file appears to be encrypted in ECB mode, as blocks of all-zeroes are always encoded the same way.

Is there any way of determining the cipher used, and what are the chances of a known plaintext attack?
All modern block ciphers are supposed to be pseudorandom permutations, meaning that they cannot be efficiently distinguished from a truly random permutation without knowledge of the key.  (If a practical distinguisher were to be found for a particular cipher, that cipher would be considered broken by modern standards.)

This also implies that no two secure modern block ciphers (with the same block size) can be practically distinguished from each other, unless one knows the key being used.  Thus, unless the cipher being used is broken, or unless you can somehow find out the key, the answer to your question is "no".