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Category:   Device (Encryption/VPN)  >   Dell SonicWALL Vendors:   SonicWALL
The VPN Implementation on SonicWALL's Tele2 and SOHO Firewalls Uses Weak IKE Authentication Keys
SecurityTracker Alert ID:  1001174
SecurityTracker URL:
CVE Reference:   GENERIC-MAP-NOMATCH   (Links to External Site)
Updated:  Mar 28 2001
Original Entry Date:  Mar 28 2001
Impact:   Disclosure of authentication information, Disclosure of system information
Vendor Confirmed:  Yes  Exploit Included:  Yes  
Version(s): firmware version
Description:   A vulnerability has been discovered in the VPN implementation of SonicWALL's Tele2 and SOHO firewalls that uses short IKE pre-share key sizes.

When using these products in a gateway-to-gateway VPN configuration using IPSec with IKE pre-shared keys, the IKE pre-shared keys are limited to 48 bytes.

The vendor has confirmed the vulnerability.

Impact:   VPN sessions that are created using short IKE pre-shared keys could be decrypted, even if long session keys are used.
Solution:   No solution was available at the time of this entry. However, the vendor is working on a firmware fix.
Vendor URL: (Links to External Site)
Cause:   Authentication error

Message History:   This archive entry has one or more follow-up message(s) listed below.
(Technical Clarifications) Re: The VPN Implementation on SonicWALL's Tele2 and SOHO Firewalls Uses Weak IKE Authentication Keys
A user provides technical clarification and disputes that this is a vulnerability.
(Additional Clarification About Security Impact) Re: The VPN Implementation on SonicWALL's Tele2 and SOHO Firewalls Uses Weak IKE Authentication Keys
This is a follow-up message that provides some additional clarification regarding security issues (or lack thereof) with 48 byte IKE pre-shared keys.

 Source Message Contents

Subject:  SonicWall IKE pre-shared key length bug and security concern

I have recently found a bug in the latest firmware 
( of SonicWall's Tele2 and SOHO firewalls.

Product details:

Bug disovery:
I was recently configuring the Tele2 and SOHO 
versions of these firewalls in a gateway to gateway 
VPN using IPSec with IKE pre-shared keys. The 
home office gateway was a Cisco PIX 520 running 
the PIX OS 5.2(4).  The Tele2 and SOHO firewalls 
were recently upgraded to the firmware.
The IPSec configuration was ESP-3DES ESP-MD5-
HMAC. During my configuration setup I noticed that I 
could not configure an IKE pre-shared key longer 
than 48 bytes.  Doing so caused the the 2nd phase 
IKE negotiation to fail on the PIX.  

I contacted the vendor (SonicWall) and reported the 
problem.  They have replicated the problem and 
confirmed that it is indeed a bug in their firmware.
I asked them for permission to inform BugTraq and 
they responded that it was indeed alright to post this 
here provided that I inform you that I found the bug 
and that to say that they will provide a fix for this 
problem as soon as possible.

Security concern:
Obviously the limitation of using only a  48 byte key 
as opposed to using a full 128 byte key degrades the 
overall security of the firewall.

Do not use pre-shared keys. Use certificates, your 
own or from a third party CA, instead.

If you must use pre-shared keys:
  Use only static gateway addresses if possible.
  Use a different key for each gateway.
  Turn on Perfect Forwared Secrecy.
  Set your key expiration time to a shorter interval.

Configuration information for duplication:
note: IP Addresses have been removed.

PIX 520 with OS 5.2(4) relavant config:
access-list 119 permit ip
access-list nonat permit ip

sysopt connection permit-ipsec
sysopt ipsec pl-compatible

crypto ipsec transform-set SonicFirewall esp-3des 
crypto map Sonic-map 19 ipsec-isakmp
crypto map Sonic-map 19 match address 119
crypto map Sonic-map 19 set peer
crypto map Sonic-map 19 set transform-set 
crypto map Sonic-map interface outside

isakmp enable outside
isakmp key <48-byte key here> address netmask
isakmp identity address
isakmp policy 19 authentication pre-share
isakmp policy 19 encryption 3des
isakmp policy 19 hash md5
isakmp policy 19 group 1
isakmp policy 19 lifetime 28800

SonicWall with firmware
Note: sonicwall config is web based so I will post
field names. datatypes in square brackets "[ ]" and 
field values after a colon ":"  IP addresses have also 
been removed.

Summary Tab:
Enable VPN checkbox: Checked
Disable all VPN Windows Networking (NetBIOS) 
broadcast [checkbox]: UnChecked
Enable Fragmented Packet Handling [checkbox]: 

Configuration Tab:
Security Association [drop-down listbox]: SonicToPIX
IPSec Keying Mode [drop-down listbox]: IKE using 
pre-shared secret
Name [textbox] SonicToPix
Disable This SA [checkbox]:UnChecked
IPSec Gateway Address [textbox]
Require XAUTH/RADIUS(only allows VPN clients) 
Enable Windows Networking (NetBIOS) broadcast 
Enable Perfect Forward Secrecy 
SA Life time (secs) [textbox]:28800
Encryption Method [drop-down listbox]:Strong 
Encrypt and Authenticate (ESP 3DES HMAC MD5)
Shared Secret [textbox]:<48-byte key here>
Destination Networks: [sub window]:
	IP Address [textbox]
	SubnetMask [textbox]

Disclaimer and closing:
I must say that I am not a security expert and I do not 
claim to be one.  My opinions are my own.  Use my 
opinions and the information in this posting at your 
own risk.  My intention for posting this information is 
to inform the BugTraq community about a possible 
security concern.

Steven Griffin


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