Hi Shiva,
The links you mention are about MD5 536445d39de9f19947aa493c1ee57751. Symantec detects that partiular file as "Trojan.Pidief" in any set of definitions since "10/15/2014 rev. 19."
There are constantly new variants of this same "Trojan.Pidief" threat in circulation, so definitely make sure that a mail security solution is in place in your organization to scan all incoming mail.
Please do take the time to update this thread and mark it solved, if this has answered your query! &: )
With many thanks,
Mick