If I add the Eicar Test Signature at the beginning of a large text file, will that file turn out to be malicious? I opened a 5 MB binary file on Sublime Text and added the signatue at the beginning. On scanning with the clamav library, it identified it as a non-malicious file. This is with the latest virus definitions. With virus definitions from a couple of days back, clam detected that file as a virus.