Technology Utilities Council (TUC)

E-mail Attachment Filtering Proposal

Approved 10-DEC-2003

(Originally submitted For Technology Committee Review 19-NOV-2003)

Attachment Filtering Model

Computer viruses are frequently spread by executable programs that are distributed as e-mail attachments. While IUP actively updates virus protection on the IUP.EDU e-mail system, there are still high risk periods for e-mail virus damage between the time that a new e-mail virus is discovered and an updated virus defense is provided by our virus software vendor.
To help reduce the spread of computer viruses and protect university resources, the IUP e-mail system will no will no longer permit delivery of e-mail messages that contain high risk attachments. Effective 5-JAN-2004, email messages that contain attachments of any of the file types noted below will not be delivered to IUP e-mail accounts. When such a message with a high risk attachment is encountered, the IUP e-mail system will return the message to the sender with a note reporting that the message cannot be delivered because it contained a potentially executable attachment.

File Types that will not be delivered

.bat	Batch file
.bas	Basic program
.chm	Compiled html help
.cmd	Windows NT Command script
.com	MS-DOS program
.cpl	Control Panel extension
.exe	Program
.inf	Set up
.hlp	Windows help file
.ht	Microsoft HyperTerminal
.hta	HTML application
.js	JScript Script file
.jse	Jscript Encoded Script file
.lnk	shortcut
.msi	install control file
.msp	Windows installer patch
mst	Visual Test Source File
pcd	Photo CD Image
.pif	Shortcut to MS-DOS program
.reg	Registration entries
.scr	Screen saver
.sct	Windows Script Component
.shs	Shell Object
.vb	VBScript file
.vbe	VBScript encoded script file
.vbs	Visual Basic Script file
.wsc	Windows Script Component
.wsf	Windows Script file
.wsh	Windows Script Host Settings file

zip (1)

Archive / Compression Files, (1)defined here to include zip plus the following file types: ACE, ARC, ARJ, BH, BZIP2, GZ, GZIP, HOX, LHA, LZH, RAR, TAR, TAR.GZ, TAR.BZ2, SEA, SIT, Z, ZOO

Notes

If there is a valid need to exchange files of the types noted above, the sender and receiver need to make alternate arrangements to exchange the file. Options include...

Change the file extension to a type that is not blocked. For example, change progam1.exe to program1.for-cosc101 and send program1.for-cosc101 via e-mail, informing the receiver to rename the file back to program1.exe.

Transfer the file using FTP. See Project Directory Service Support Resources for details.

Post the file to a web site. See Personal Web Page Support Resources for details.

For help with any of these approaches, please contact your technology support representative. See also www.iup.edu/ats/Helpdesk/email/efilter.shtm.
Please Note that it is very important to recognize that attachment filtering does not eliminate all virus and security risks. Beyond the file types list above, there are other file types that contain malicious content. Users must approach e-mail messages with attachments or embedded HTML with extreme caution. Do not open attachments from an untrusted origin and never open attachments that appear suspicious in any way. If you do not recognize the attachment type, do not open it. By opening such attachments, you not only place your own PC at risk, you also potentially expose any network drive to which you are attached! If in doubt, do not open the attachment! Contact your tech support group or delete the message.

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