Hello,
W32.Changeup.C is a worm that spreads through removable and shared drives by exploiting the Microsoft Windows Shortcut 'LNK' Files Automatic File Execution Vulnerability (BID 41732).
W32.Stuxnet!lnk is a detection for .lnk files created by the W32.Stuxnet worm.
Bloodhound.Exploit.346 is a heuristic detection for files attempting to exploit the Microsoft Windows Shortcut 'LNK' Files Automatic File Execution Vulnerability (BID 41732).
New Trojan.Shylock wave
https://www-secure.symantec.com/connect/blogs/new-trojanshylock-wave
The Shylock “LNK” Awakening
https://www-secure.symantec.com/connect/blogs/shylock-lnk-awakening
Could you please zip each of the files and submit the zip files (without password) to the Symantec Security Response Team on :
https://submit.symantec.com/websubmit/essential.cgi
We also offer a self-service site to analyze files, at http://www.threatexpert.com, which can give you more information on the files you submit to it.
Check these Articles:
What to do when you suspect that a Symantec AntiVirus product is not detecting viruses
http://www.symantec.com/docs/TECH99222
Using Symantec Help (SymHelp) Tool, how do we Collect the Suspicious Files and Submit the same to Symantec Security Response Team.
https://www-secure.symantec.com/connect/articles/using-symantec-help-symhelp-tool-how-do-we-collect-suspicious-files-and-submit-same-symante
So, as we see these above Threats appears when there are open vulnerabilities on the machines.
In your case, I would suggest the below Plan of Action:
1) Make sure ALL Computers are installed with Symantec EP with latest / updated with virus defintions.
2) Install ALL Latest Microsoft Secuirty Patches / Sevice Packs on ALL machines.
3) Make sure ALL the client machines are using the Latest Vendor Patches installed.
4) Disable Auto play with GPO
http://support.microsoft.com/kb/953252
5) Disable the System Restore with GPO
http://support.microsoft.com/kb/283073
6) Disable Scheduled Tasks with GPO
http://support.microsoft.com/kb/310208
7) Incase of any shared / mapped drives present, make sure these are password protected.
8) Scan ALL the machines...
Here are some excellent suggestions on how to keep your computers, their users and data safe:
http://www.symantec.com/theme.jsp?themeid=stopping_malware&depthpath=0
Hope that helps!!