KPMG-2002030: Watchguard Firebox Dynamic VPN Configuration Protocol DoS

[Peter Gründl <pgrundl () kpmg dk>]

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Title: Watchguard Firebox Dynamic VPN Configuration Protocol DoS

BUG-ID: 2002030
Released: 9th Jul 2002
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Problem:
========
A malicious user can crash the Dynamic VPN Configuration Protocol
service (DVCP) by sending a malformed packet to the listener service
on TCP port 4110.


Vulnerable:
===========
- Watchguard Firebox firmware v5.x.x

Not Vulnerable:
===============
- Watchguard Firebox firmware v6.0.b1140


Product Description:
====================
Quoted from the vendor webpage:

"The WatchGuard® Firebox System is a powerful security solution that
 gives small and medium sized businesses, central offices, and VPN
 hubs integrated firewall protection and VPN support."

"About DVCP
 DVCP is a WatchGuard client server protocol that securely transmits
 IPSec VPN configuration information to WatchGuard Fireboxes. Network
 administrators use WatchGuard software to define each configuration
 aspect of the VPN, such as encryption algorithms and how often keys
 will be negotiated, then the settings are stored on a centrally
 located DVCP Server.When a Firebox is installed and initialized with
 software and instructions, a software client on the Firebox contacts
 the central DVCP server to obtain IPSec policy information using a
 secure protocol."


Details:
========
The DVCP service can be crashed using anywhere between 1 and 400
packets of tab characters, followed by a CRLF. The firewall needs to
be rebooted for the DVCP service to function again.


Vendor URL:
===========
You can visit the vendor webpage here: http://www.watchguard.com


Vendor response:
================
The vendor was notified on the 8th of May, 2002. On the 23rd of
May, 2002 the vendor notified us that the issue would be resolved
in the next version (6.x). On the 9th of July we verified that
the problem was resolved in the new firmware version.


Corrective action:
==================
Upgrade to firmware version 6.x, available at the livesecurity
website. If you are not a subscriber to the livesecurity service,
please contact Watchguard support further assistance.



Authors:
Andreas Sandor (asandor () kpmg dk)
Peter Gründl (pgrundl () kpmg dk)

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