On Tue, 25 Dec 2001, Marc SCHAEFER wrote:

> Zyxel Prestige SDSL Router IP Packet Length Remote Denial Of Service Vulnerability
> BugTraq ID: 3695
> Remote: Yes
> Date Published: Dec 14 2001 12:00A
> Relevant URL:
> http://www.securityfocus.com/bid/3695
> Summary:
> 
> Prestige is a product line of DSL routers produced and distributed by
> Zyxel.
> 
> A problem with Zyxel routers has been discovered that could lead to a
> remote denial of service attack.  The problem is in the receipt of
> malformed packets.
> 
> When a Zyxel router receives malformed packets crafted with an IP length
> shorter than the actual size of the packet, the router becomes unstable
> and drops connectivity.  This loss of connectivity can last up to three
> minutes.  This could lead to a remote user denying service to a legitimate
> user of the router.  The router is affected only by malformed packets
> received through the DSL interface.  Malformed packets sent through the
> LAN interface have no affect on the system.
> 
> The router is affected only by malformed packets received through the DSL
> interface.  Malformed packets sent through the LAN interface have no
> affect on the system.
> 
> This problem has been reported in the model 681 routers, and may affect
> others in the Prestige product line as well.
> 
> [ Pas libre: firmware propri�taire. Mais vu que cela peut concerner un
>   syst�me libre aussi ... ]
> 
> ...
> 
> Zyxel Prestige SDSL Router IP Fragment Reassembly Vulnerability
> BugTraq ID: 3711
> Remote: Yes
> Date Published: Dec 18 2001 12:00A
> Relevant URL:
> http://www.securityfocus.com/bid/3711
> Summary:
> 
> Prestige is a product line of DSL routers produced and distributed by
> Zyxel.
> 
> A problem with Zyxel routers has been discovered that could lead to a
> remote denial of service attack.  The problem is in the receipt of
> fragmented packets.
> 
> When a Zyxel router receives fragmented packets that after reassembly is
> greater than 64 kilobytes in length, the router crashes.  The router must
> be power cycled to resume normal operation.  This could lead to a remote
> user denying service to a legitimate user of the router.
> 
> The router is affected only by fragmented packets received through the DSL
> interface.  Fragmented packets sent through the LAN interface have no
> affect on the system.
> 
> This problem has been reported in the model 681 routers, and may affect
> others in the Prestige product line as well.
> 
> [ idem ]

Si je comprend bien, cela ne concerne que les routeurs, et non les modems
utilis� via pppoe?! Me semble que ce type de probl�mes se situerait au
niveau de pppoe, mais je ne suis pas s�r de tout bien comprendre...

Si oui, pppoe est-il vuln�rable?

--
 F�lix Hauri  -  <[EMAIL PROTECTED]>  -  http://www.f-hauri.ch



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