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Block Attachment with free Webmail sites

Posted on 2007-12-02
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Last Modified: 2008-11-17
Dear All
I have in my network ISA server 2004 & Websense server, what I need to know. Is there any way to allow users access to free webmail servers (like hotmail.com or yahoo.com) and in the same time prevent them to send any attachments using those servers? So they can only send Email without any attachments?
Thanks in advance for your sincere cooperation.
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Question by:melnahas
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Expert Comment

by:mcse2007
ID: 20393787
I don't ISA can filter the packet of hotmail and block any attachment to outgoing email. ISA is not that clever yet to do this kind of task.
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Bing CISM / CISSP earned 125 total points
ID: 20393930
it is possible, if an attachment related activity can be determined by filtering its URL.

actually, it depends on how the free webmail providers deal with attachments. for example, you may prevent hotmail users adding an attachment by filtering the following URL.

*.mail.live.com/mail/AddAttachmentLight.aspx?* (where * is wildcard)

FYI - HTTP Filtering in ISA Server 2004
http://www.microsoft.com/technet/isa/2004/plan/httpfiltering.mspx

hope it helps,
bbao
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Author Comment

by:melnahas
ID: 20395138
i can't block certain URL for delivering mail attachments, as there are a lot of free webmail servers. but if there are any addons for ISA 2004 that make this process, it will be a great help to inform me about it
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by:Keith Alabaster
ID: 20395275
You can certainly do it - either with add-ons or without. Doing it without is harder though.

Right-click your outbound http rule and select configure http
In here you will see the options for signatures, headers and the like.

YOU will need to identify the headers and signatures you want to block though.
Assumning you have ISA2004 sp3 installed, using the monitoring-logging section of the ISA gui you can drill down and see the http headers and user-agents that are used when posts are made for attachements etc.
Because the configure http option is set for that specirfic rule onl;y (not globally) you can define and refine your rules to allow what you want at a good level of granularity - but it takes time and effort to get it right.

Some of the add-ons from Websense, GFI Web Monitor etc can also do this - most of these have a 30 day eval that you can downlaod and install and test with.

Keith
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by:Bing CISM / CISSP
ID: 20395295
a lot of vendors do development for ISA servers since ISA 2000. unfortunately, AFAIK, there is no such as an add-on that only black web email's attachment.

however, you may search MS partner's solution catalog for a possible solution.

Solutions directory
https://solutionfinder.microsoft.com/SDK/Solutions/SolutionsDirectory.aspx

hope it helps,
bbao
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Expert Comment

by:Keith Alabaster
ID: 20395314
It would have to be done with combinations  ie www.blockme.webmail.com/mail_attach.asp & Header:post etc
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LVL 37

Expert Comment

by:Bing CISM / CISSP
ID: 20395415
the link is not workable. :(
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by:Keith Alabaster
ID: 20395425
lol - it was an example :)

The url of the web site plus the post http headers.
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by:Bing CISM / CISSP
ID: 20395454
lol - it looks like what i mentioned in my first comment. :)
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by:Keith Alabaster
ID: 20395458
Agreed :)
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Author Comment

by:melnahas
ID: 20405028
so we are back to the first solution, which will require to know all the URLs of attaching pages, and there are noway to know all webmail servers attaching pages URLs.
concerning websense there are a solution but for IM attaching, but not for webmail attaching.
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Expert Comment

by:Bing CISM / CISSP
ID: 21156385
> there are noway to know all webmail servers attaching pages

it is possible, as i showed in the first post. however, there is no a regular way to determine the attaching URLs. it depends on the particular vendors.

sometimes a right answer does not mean a right solution...

hope it helps,
bbao
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by:Computer101
ID: 21186073
Forced accept.

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