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Re: Netgear DG632 Router Remote DoS Vulnerability
From: "Tom Neaves" <tom () tomneaves co uk>
Date: Mon, 15 Jun 2009 23:11:27 +0100


I see where you're going but I think you're missing the point a little. By *default* the web interface is enabled on the LAN and accessible by anyone on that LAN and the "remote management" interface (for the Internet) is turned off. If the "remote management" interface was enabled, stopping ICMP echo responses would not resolve this issue at all, turning the interface off would do though (or restricting by IP, ...ack). The "remote management" (love those quotes...) interface speaks over HTTP hence TCP so no amount of dropping ICMP goodness will help with this. Anyhow, I am happy to discuss this off list with you if its still not clear to save spamming everyone's inboxes. :o)


----- Original Message ----- From: Alaa El yazghi
To: Tom Neaves
Cc: bugtraq () securityfocus com ; full-disclosure () lists grok org uk
Sent: Monday, June 15, 2009 11:03 PM
Subject: Re: Netgear DG632 Router Remote DoS Vulnerability

I know and I understand. What I wanted to mean is that we can not eventually acces to the web interface of a netgear router remotely if we cannot localy. As for the DoS, it is simple to solve such attack from outside. We just disable receiving pings (There is actually an option in even the lowest series) and thus, we would be able to have a remote management without ICMP requests.

2009/6/15 Tom Neaves <tom () tomneaves co uk>


I'm not quite sure of your question...

The DoS can be carried out remotely, however one mitigating factor (which makes it a low risk as opposed to sirens and alarms...) is that its turned off by default - you have to explicitly enable it under "Remote Management" on the device if you want to access it/carry out the DoS over the Internet. However, it is worth noting that anyone on your LAN can *remotely* carry out this attack regardless of this management feature being on/off.

I hope this clarifies it for you.

----- Original Message ----- From: Alaa El yazghi
To: Tom Neaves
Cc: bugtraq () securityfocus com ; full-disclosure () lists grok org uk
Sent: Monday, June 15, 2009 10:45 PM
Subject: Re: Netgear DG632 Router Remote DoS Vulnerability

How can it be carried out remotely if it bugs localy?

2009/6/15 Tom Neaves <tom () tomneaves co uk>

Product Name: Netgear DG632 Router
Vendor: http://www.netgear.com
Date: 15 June, 2009
Author: tom () tomneaves co uk <tom () tomneaves co uk>
Original URL: http://www.tomneaves.co.uk/Netgear_DG632_Remote_DoS.txt
Discovered: 18 November, 2006
Disclosed: 15 June, 2009


The Netgear DG632 router has a web interface which runs on port 80.  This
allows an admin to login and administer the device's settings.  However,
a Denial of Service (DoS) vulnerability exists that causes the web interface
to crash and stop responding to further requests.


Within the "/cgi-bin/" directory of the administrative web interface exists a file called "firmwarecfg". This file is used for firmware upgrades. A HTTP POST request for this file causes the web server to hang. The web server will stop responding to requests and the administrative interface will become inaccessible
until the router is physically restarted.

While the router will still continue to function at the network level, i.e. it will still respond to ICMP echo requests and issue leases via DHCP, an administrator will
no longer be able to interact with the administrative web interface.

This attack can be carried out internally within the network, or over the Internet if the administrator has enabled the "Remote Management" feature on the router.

Affected Versions: Firmware V3.4.0_ap (others unknown)


12 June, 2009 - Contacted vendor.
15 June, 2009 - Vendor responded. Stated the DG632 is an end of life product and is no longer supported in a production and development sense, as such, there will be no further
firmware releases to resolve this issue.


Discovered by Tom Neaves

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