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                Date: 1998-08-05
                 
                 
                Micro/soft ferngesteuert: Back Orifice follow/up
                
                 
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      q/depesche 98.8.5/3 
updating   98.8.5/2 
 
Micro/soft ferngesteuert: Back Orifice follow/up 
 
Sogar die coolen NT/Inschinöre rund um ntbugtraq.com machen 
sich ihre Nacht/gedanken, obwohl sie das 
win95-98/spezifische "Back Orifice" eigentlich nichts 
angeht.  
 
Vielleicht, weil das trojanische Client/Programm mit <125 Kb 
so winzig ist, dass es sich ziemlich leicht verstecken 
lässt? 
Vielleicht, weil BO auch hinter Firewalls ´funktioniert? 
Vieleicht, weil ein normaler Virenscanner darauf nicht 
reagiert? 
Vielleicht auch, weil eine NT/Version als Follow/up nicht 
ganz undenkbar ist? 
 
Wer BO suchet, wird es nächst toten Kühen finden: 
 
http://www.cultdeadcow.com
                   
 
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Though not specific to NT security there has been much talk 
about Back Orifice lately.  I've played around with it a bit 
and here is a way to find it and get rid of it. 
 
Default installation: Installs a 122k - 123k file called " 
.exe" in c:\windows\system with a modified date of 7/11/95. 
Changes 
HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices\Default 
from blank to " .exe". Transmits data on UDP Port 31337 - 
it's in the readme 
 
An attacker can modify these defaults to be anything they 
like but if you check the registry entries under 
HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices 
and find one you are not familiar with (not the task 
scheduler, not a virus scanner, etc) that runs a 122k - 123k 
file (does not have to be an exe) from your 
c:\windows\system folder, it might be worth investigating 
further.  The file could probably be padded to be a 
different size or the code could be modified to mutate its 
size to help hide it.  There was some speculation in some of 
the media reports that a virus detection program might be 
able to detect the program in action.  Network Associates 
McAfee Virus Scan did not set off any alarms.  Maybe another 
virus scanner will view the program's actions as suspicious? 
 
Unless there are hidden "features" (still letting it run 
behind a firewall logging all traffic on the Back Orifice 
machine as a test to see if there is more to it) it is just 
a useful remote admin tool in a semi-GUI box that can be 
custom packaged to take advantage of existing Win9x security 
flaws. 
 
relayed by ways of http://www.ntbugtraq.com
                   
 
from jimst@enteract.com 
 
 
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TIP 
Download free PGP 5.5.3i (Win95/NT & Mac) 
http://keyserver.ad.or.at/pgp/download/
                   
 
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edited by  
published on: 1998-08-05 
comments to office@quintessenz.at
                   
                  
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