Virus?
it might be a false positive... ask him to submit a report to avast virus lab, so that they can check it and whitelist it... you can check a website for malicious codes in https://www.virustotal.com... that's really a useful tool with 50+ AV services... it says your site is clean 
We can't help everyone, but everyone can help someone - Ronald Reagan
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Don’t Forget to “Mark as Solved” after the fix
Did you know? Your question has already been answered. But you haven't searched it yet.
Don’t Forget to “Mark as Solved” after the fix