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RE: Yahoo Messenger Stale Sessions
From: <Leonard.Ong () nokia com>
Date: Fri, 15 Nov 2002 16:25:01 +0800


Of course, logically, you would offload your server. ICQ, MSN, Yahoo, will try its best to connect directly between 
peers, and if they can't, they will have to route it through their server.  I tried Yahoo Voice chat, if I use 
unrestricted Public IP, I can see I have direct connection with peers.  However, If i'm behind NAT and enables 
firewall, it will contact Yahoo Server as intermediate hop between peers.

It is exploitable, since your peer might tbe using a dial-up ip address.  The next user can get this IP address, run 
sniffer, find that yahoo in sending a packet to you (even if you dont' have yahoo), then use the knowledge to exploit 
the established session.  Like saying ' Hi, I don't like you', identity impersonation - repudiation

Leonard Ong
Network Security Specialist, APAC

Email.  Leonard.Ong () nokia com
Mobile. +65 9431 6184
Phone.  +65 6723 1724
Fax.    +65 6723 1596

-----Original Message-----
From: ext phani () myrealbox com [mailto:phani () myrealbox com]
Sent: Thursday, November 14, 2002 1:14 PM
To: security-basics () securityfocus com
Subject: Re: Yahoo Messenger Stale Sessions

On Mon, Nov 11, 2002 at 11:04:50AM +0800, Leonard.Ong () nokia com wrote:
   It is surprising that Y! makes a direct connection to the peer. I thot that Y! connects to the server and that 
handles the communication.
  And what is the vulnerability that u look at. Since the connection is a p2p connection, I think there can be no 
vulnerabilities. Correct me if i am wrong.

Hello All,

During my observation in daily use of Yahoo Messenger, my computer has "stale/zombie" sessions.  For example, If i 
have received/message a friend, yahoo will normally make a direct connection from my PC to my friend.  From Netstat 
result, you can see a high port on my computer is having an Established session with my peer's:5101 port.

The issue is, after a contact has gone offline (dial-up), the state established in the netstat will remain until the 
next day.  I wouls see this as a vulnerabilities, since an arbitrary user can assume the IP Address was used 
(dial-up->dynamic ip assignment), and use this established session to assume it.

Any idea ?

Leonard Ong
Network Security Specialist, APAC

Email.  Leonard.Ong () nokia com
Mobile. +65 9431 6184
Phone.  +65 6723 1724
Fax.    +65 6723 1596

-----Original Message-----
From: ext Joey [mailto:josefhuggins () hotmail com]
Sent: Saturday, November 09, 2002 9:32 PM
To: Security Basics
Subject: Re: Biometric question

To clarify:retinal scanning is about as effective as fingerprints. Retinal
scanning uses a laser light, often in the green part of the spectrum to scan
the blood vessels of the internal eye. Both methods scan around 90 metric
points. They can easily read false depending on whether or not the
biological sample (in this case eyeball or finger) is placed exactly in the
same position as it was when it was initially scanned. There is, of course,
with most software a threshold setting which will allow readings to require
either a very precise ( a finger must be placed in exactly the same spot
every time on a reader ) or very minimal ( a finger can be placed anywhere
near the center of the reader, but the accuracy drops proportionately )
setting. The best way to go from everything I've seen and read is with iris
scans. Whereas fingerprint and retina scans read around 90 metric points, an
iris scan reads about 250. Iris scans are non-invasive whereas retina scans
require a laser light or other strong light source directed through the
cornea in order to read the vessel pattern in the back of the eye. While
it's allot more expensive, if security, and not money is your concern, I
think iris scanners are the way to go. If you can't "hack" it and you have
to settle w/fingerprint or retinal scanners, I would go for the fingerprint


----- Original Message -----
From: Naveed Ahmed <naveed.ahmed () vinciti com>
To: <msconzo () tamu edu>; <security-basics () security-focus com>
Sent: Thursday, November 07, 2002 11:05 AM
Subject: RE: Biometric question

Michael is right.
the better ones are ( at least relatively more difficult to fake) retina
scans and  voice recognition.
dont go by what tom cruise does in 'minority report' with the eye

-----Original Message-----
From: Michael Sconzo [mailto:msconzo () tamu edu]
Sent: Thursday, November 07, 2002 10:43 PM
To: security-basics () security-focus com
Subject: RE: Biometric question

Hash: SHA1

One of the more memorable things that I have read about fingerprint
scanners is:

You can basically fake a fingerprint biometric machine with a gummi
bear.  If I remember correctly, the majority of fingerprint scanners
are vulnerable to this type of attack. One of the big things to look
for is one that samples SHAPES not POINTS, and remember the more the

As for other types of biometrics, I am not too sure, hopefully
somebody else can shed some light on those.

- -mike

- -----Original Message-----
From: Felix Cuello [mailto:felix () qodiga com]
Sent: Wednesday, November 06, 2002 1:27 PM
To: security-basics () security-focus com
Subject: Biometric question

Hello list!

   I will work in a project where phisical security will be based on
   biometrics, in fact only will be based on fingerprints biometric.

   How secure are fingerprints?, what biometric are more secure?
   eye, ??? what else).

   I'm not a security expert :-)

   Thanks a lot,

   [my english is bad... please sorry :-)]

- --
Felix Cuello
felix () qodiga com

Av.Santa Fe 882 P.13 Of. "E"
C.P. ABP1059C
Tel.: (54) 011 - 4312-1698
Buenos Aires - Argentina

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