Security Incidents: RE: Yahoo Messenger Stale Sessions

["David Gillett" <gillettdavid () fhda edu>]

  Not so arbitrary.  He needs to not only spoof the IP 
address your friend had, but also get the other port number 
and the TCP sequence number right.  Which might not be much
challenge *IF* he was able to sniff your original conversation.
(If he's spoofing rather than assuming the address, he'll need 
to sniff your machine's responses....)

  That much probably limits it to people within either your,
or your friend's, network provider.  Then there's the question
of what to do with this connection.  Is there a vulnerability
in Yahoo Messenger that could be exploited from there?  (If
so, should you be using it at all?)

David Gillett


> -----Original Message-----
> From: Leonard.Ong () nokia com [mailto:Leonard.Ong () nokia com]
> Sent: Tuesday, November 12, 2002 5:39 PM
> To: incidents () securityfocus com
> Subject: RE: Yahoo Messenger Stale Sessions
>
>
> 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 ?
>
>
> Regards,
> Leonard Ong
> Network Security Specialist, APAC
> NOKIA
>
> Email.  Leonard.Ong () nokia com
> Mobile. +65 9431 6184
> Phone.  +65 6723 1724
> Fax.    +65 6723 1596
>
>
>
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