RE: Reverse http traffic

["Jim Butterworth" <my.dsl () verizon net>]

If this just all of a sudden started happening, then I would tend to
lean towards:

#1 - a recent config change (ie, software or patches)
#2 - renew DHCP/MAC seats on router
#3 - look at inbound traffic for questionable activity

I believe Daniel has indeed stated he was looking at a questionable
inbound connection.

Once you establish this, try running fscan and fport (freeware) to see
which ports are open and which applications or processes are mapped to
them.  Do this while connected so that you will see the activity while
it is occurring.  

I've purchased nameless firewall/spyware/av software only to learn that
they all would negotiate their own connections without permission.  When
I  contacted them about it, they claim it is for "update checking".
Isn't that irony?  Buy a firewall only to have the firewall break your
rules!

You can also try and run a program called "Hijack This", which will tell
you all of the things that are currently running, including registry
calls...

Or, plug the computer back in, and from the cmd line, run netstat -an
and see who/what/when is established/waiting/listening.  

Happy hunting!
Jim  




-----Original Message-----
From: Jarrod Frates [mailto:fusion () illuminus com] 
Sent: Tuesday, December 30, 2003 1:57 PM
To: incidents () securityfocus com
Subject: RE: Reverse http traffic

I've run into something similar to this on systems where Norton
Anti-Virus
and a Sygate firewall were installed simultaneously.  If this is the
case,
try disabling the Sygate firewall service from the Services MMC and see
if
you can access HTTP and mail services.  Sometimes you can get normal
service
back by re-enabling the firewall after about five minutes.  So far as I
have
seen, there is no way to permanently get around it other than by
removing
one of the two products.


Jarrod

-----Original Message-----
From: Daniel H. Renner [mailto:dan () losangelescomputerhelp com] 
Sent: Tuesday, December 30, 2003 12:33 PM
To: incidents () securityfocus com
Subject: Reverse http traffic

Hello,

I had a case recently wherein one of a client's systems (Win2k) could
not
access http, or mail traffic.  At the same time, 2 other systems
(Win95 and Xandros) could, and yet he could access all of the other
network
shares via TCP.

He brought it to my shop, it was patched up, already had the latest
anti-virus defs, and it got on the 'net fine here.  He returned with it
and
set it up - and could not get any http or email.

I went to his office to see what was up, hooked in my little 'kneetop'
(Sony Picturebook) and browsed just fine.

I then installed a Linux firewall on a spare computer, replaced the
Linksys
router with it and instantly his Win2k was able to browse and get email.

I checked the firewall logs and saw quite a few attempts from a Google
IP
address (whois-ed, but I'm not ignoring that it was possibly spoofed)
that
was sending IN traffic with a source port of 80 and a destination port
in
the temporary range (33xx) - eh???

I can speculate (otherwise known as 'assume' :) that this site was
trying to
spoof my client's system into accepting some traffic by using a
reverse-flow, but...

Can anyone tell me what actually could cause this?


-- 


Thank you,

Dan Renner
President
Los Angeles Computerhelp
http://losangelescomputerhelp.com
818.352.8700



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