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RE: Skype bypasses Windows XP Firewall
From: "Roger A. Grimes" <roger () banneretcs com>
Date: Fri, 17 Jun 2005 13:56:14 -0400

Any time you execute any executable, it can modify any program or OS's
behavior. This is not limited to Windows, it can occur with any OS where
the user is logged in as admin or root. Microsoft has even published an
API which can be used by software developers to modify the Windows
Firewall behavior.

It goes back to the #1 security mantra, if you run an executable on your
computer it can do anything it wants.


*Roger A. Grimes, Banneret Computer Security, Computer Security
*CPA, CISSP, MCSE: Security (NT/2000/2003/MVP), CNE (3/4), CEH, CHFI
*email: roger () banneretcs com
*cell: 757-615-3355
*Author of Malicious Mobile Code:  Virus Protection for Windows by
*Author of Honeypots for Windows (Apress)


-----Original Message-----
From: David Low [mailto:david.low () imcorporation com] 
Sent: Thursday, June 16, 2005 9:04 PM
To: security-basics () securityfocus com
Subject: RE: Skype bypasses Windows XP Firewall

Dear All,

I'm wondering does anyone have clue regarding Skype (A free internet
VOIP thingy : http://www.skype.com) which bypasses Windows XP SP2

It just automatically adds itself to the exception list without user

But if u were to use ZoneAlarm, the ZA is still able to detect and block

It there something lagging in the Windows Firewall or is it the program
which can bypass it.

If you require further assistance or would like more details, please do
not hesitate to contact us.
David Low
System / Network Engineer
I'M Technologies Ltd
51 Changi Business Park Central 2
# 09-13 The Signature
Singapore 486066 

DID: (65) 6780 0815
Fax: (65) 6789 3980

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