Re: DoS Alcatel ADSL Modem Speed Touch Home

[Cyber Hunter <cyber_hunter () LINUXBR COM BR>]

I am using ADSL too , with NT 4.0 , but without any firewall system or nat ,
and the same problem happen with me , I thought that was a problem with
WinNT , so I reinstalled it , but now I can see that others have the same
problem .For me , the crash happen when I do a syn scan , from inside or
outside.
Of course that ADSL have a DoS already relatted , but for Xnix platform ( a
PPPoE DoS ) , not NT.


----- Original Message -----
From: Ed Rolison <ed.rolison () BYZANTIUM COM>
To: <VULN-DEV () SECURITYFOCUS COM>
Sent: Friday, February 23, 2001 6:03 AM
Subject: Re: DoS Alcatel ADSL Modem Speed Touch Home


> > Hi,
> >
> > While playing around with my new ADSL connection I found out that when
you
> > portscan the ADSL modem it crashes.
> > I used NMAP and tried it locally -nmapping rfc1918 IP- and also from
outside
> > nmapping through mine PPTP connection, in both cases after a while the
modem
> > crashes, and the only thing I can do is reset the Modem.
> >
> >
> > I tried to upgrade the firmware but the problem stays.
> > I used KHDSAA 134 (988348) and KHDSAA 132 (986865)
>
> Is your ADSL NATing? If so, then if you scan from inside, then it opens
NAT
> connections, and has to maintain an entry in a connection table.
>
> Do a portscan, and it has to maintain a LOT of NAT connections (one per
port per
> host) and this can rapidly cause memory exhaustion.
>
> Your router is not the only NAT device which exhibits this problem :)
>
> (I'm assuming stuff, based on your mail but the fact that you are using
RFC1918
> indicates that there is NAT in there somewhere :))
>
> --
> Ed Rolison
> Systems Admin
> ER706-RIPE
> ed () byzantium com