Re: [malware-list] Threat model for Unix Computers

[Jörg Ostertag]

Am Mittwoch, 6. August 2008 03:44 schrieb Theodore Tso:
> On Tue, Aug 05, 2008 at 08:46:00PM -0400, Rik van Riel wrote:

...

I'm trying to fill in some other thread models, not all directly related to 
virus-scanning, but if we want to get a complete anti-threat model for linux, 
we should take them into account too.
In addition I'll add some usage scenarios for later extracting some threat 
scenarios ...

Desktop-Users:
----------------------
> 	The Linux Desktop (where clueless users may be tricked into
> 		running malware).

I would add the chance of users exporting there locally stored Files via CIFS, 
SMB, http, ... for accessing them with there beloveled streaming clients.

Speaking of exporting Files from a Desktop PC  we should also take in account 
File-Sharing clients.

Some more examples of a Desktop Users desire would be:
	- copying Files to/from there PDA (BT,USB,WLAN)
	- sharing internet connection with there PDA (BT,USB,WLAN)

Another threads would be:
	- giving access to the Desktop-PC to guest-users for
		 "just let me look up something in the internet"
	  and the guest-user on the Desktop not informing about the (in his point of
	  view) urgent installation of there beloved 
	  Browser-malware^H^H^H^H^H -adware ^H^H^H^H^H -extention

For all the Files stored on the Desktop PC we should also take in account, 
that the paranoid Desktop user would store them inside a crypted 
device/container. Some examples would be: truecrypt-container/-partition, 
External crypted Harddrive, ...

... speaking of storing Files I would expect even Desktop Homeusers to store 
there Files on a local mini Fileserver (like a Fritz-Box, NSLU2, ...) to 
share them with other devices like Multimedia players, ...

Notebook-Users:
------------------------
And then we have the Linux Notebook users. I separate these from the Desktop 
users, because they will have most of the Scenarios for Desktop users plus 
some additional treats.
	- Connecting to random accesspoints (Airports, Hotels, ...)
	- Exporting there Wireless (BT,WLAN,UMTS, ...) to random people. Sometimes
	  willingly, sometimes unwillingly
	- leaving there Notebooks unattended
		- without Bios password
		- without HDD-encrytion
		- without Boot-Manager Password
		- without screenlock
		- ...

Linux Desktops in public places:
--------------------------------------------
I'm thinking of Linux Desktop PCs in places like Internet-Cafe, 
Public-Library, School, ...
These would be similar to the Standard Linux Desktop but adding some 
additional threats.
	- willingly trying to attack the PC with physical access to 
		- CD-Rom
		- USB-Devices
			USB-Stick
			Card Reader
		- Network cable
		- Floppy drive (if still existing)
		- Reset Button
	

> 	The Linux File Server (where it is *highly* unlikely to have
> 		active running malware, since there are no clueless
> 		users running on said file server), but where malware
> 		may be stored and read over CIFS, NFS, etc.

Maybe it "was" unlikely, but you can see more and more 
(Now-)Unix-administrators originally used to other operating systems and with 
a different view to security. So it would be nice if we would be able to 
protect these users/admins/installations too. 

Mail-Proxy:
--------------
> 	The Linux Mail server is really a restricted case of the Linux
> 		Fileserver; where the only way in is SMTP, and the
> 		only protocol out is IMAP/POP.

I would add SMTP for the outgoing channel too.


Web-Proxy:
----------------
Only to complete the list:
              The Linux Web Proxy is another example of a Linux Server.
		The way in would be http traffic (mostly over port
		80 and 443) and the way out will be either over a shared
		proxy port or offered transparent if the Linux machine is used 
		as router.

In my opinion all good webproxies with scanner already provide a pretty good 
solution here.



-- 
Jörg Ostertag - Manager UNIX SW Development - Avira GmbH
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