How to convert an MD5 hash into shadow format
 

I am trying to use John the Ripper but it doesn't take regular MD5 hashes, only shadow MD5 hashes. For example this hash: 900150983cd24fb0d6963f7d28e17f72 (which, decrypted, is 'abc') within a text file, John the Ripper does not detect because it is not shadow format. How can I convert this MD5 hash into shadow format?

What you actually do not want to do is introduce a salt as this complicates things. There are contribs for JTR that handle raw MD5 hashes. Search the http://openwall.info/wiki/john for patch nfo.