NIST also publishes MD5 hashes of every file in the NSRL. This is called the Reference Data Set (RDS). When looking at an unknown file, a good place to begin is to compute its MD5 hash and compare it against the RDS. If the hash value is found in the RDS, your file is probably...
NSRL Trivia: Currently 374,830,226 rows of hash values from software applications representing the year 2000 to present day. 98,684,806 unique MD5/SHA1 hash values from the aforementioned.