Great Circle Associates Firewalls
(January 1995)
 

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Subject: Re: Web Browser-Firewall Question (fwd)
From: Brent @ GreatCircle . COM (Brent Chapman)
Date: Tue, 31 Jan 1995 17:21:36 -0500
To: Frank Wortner <frank @ prodigy . com>, "Dr. Frederick B. Cohen" <fc @ all . net>
Cc: Firewalls @ greatcircle . com

At 10:35 1/31/95, Frank Wortner wrote:
>On Monday, 30 Jan 1995, Dr. Frederick B. Cohen wrote:
>
>>       The real problem you will encounter is likely that W3 is not
>> secure.  For example, .ps files which alter internal files will pass
>> throuhg the firewall to the W3 browser and cause internal damage.
>>
>
>The problem you describe isn't limited to W3 browsers.  In fact, *any*
>system which allows the blind invocation of programs is vulnerable.  One
>could just as well send the PostScript "nastygram" you describe through
>email.  An email user agent that "conveniently" started a PostScript
>viewer would basically defer any security policy enforcement to the
>viewer just as effectively as a W3 browser.

But W3 browsers that do this (most of them) are much more common than email
agents that do this (few of them).


-Brent

--
==  For info about the Internet Security Firewalls Tutorial and a schedule  ==
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==============================================================================
==  Brent Chapman                                 Great Circle Associates   ==
==  Brent @
 GreatCircle .
 COM                         1057 West Dana Street     ==
==  +1 415 962 0841                               Mountain View, CA  94041  ==



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