SonicWall VPN/Firewall Appliance - DoS, ARP Flood, Network mapping vulnerability

Type securityvulns
Reporter Securityvulns
Modified 2004-03-04T00:00:00



SonicWall Firewall/VPN Appliance

Product History:

SonicWALL's family of Internet security appliances provide the first line of defense against Internet security threats. They include an ICSA- certified, stateful packet inspection firewall, IPSec VPN for remote access, IP address management features, and support for SonicWALL value- added security services.

Vulnerability: DoS, ARP Flood, Network mapping

Date of discovery: January 26th, 2004

Reported to SonicWall: January 27th, 2004

Confirmed by SonicWall: February 16th, 2004

Release date: March 1st, 2004

Product: SonicWall Firewall/VPN Appliance

Tested vulnerable Firmware Revisions:

Tested but Not vulnerable:

Sonic OS 2.0 and above

Firmware patch: Available. Customers must call SonicWall tech support for more details

Technical details:

Problem #1: When the device encounters an ARP request on its External (WAN) interface the SonicWall will check its Internal interface (LAN) ARP Cache to see if knows about the requested IP. Upon finding the requested IP in its ARP Cache the Sonic Wall will respond with an ARP reply on behalf of the IP being ARPed.

Problem #2 If the Sonic Wall does not find the IP in its ARP Cache and the IP being ARPed is part of a network that is attached to the LAN interface of the Sonic Wall, it will proxy the ARP request from the WAN interface through to the LAN interface.

Problem #3 For each single ARP request that the Sonic Wall proxies from the WAN interface it will make 3 ARP broadcast requests on the LAN side, effectively amplifying each WAN received request at a 3:1 ratio.

Misc information:

The ARP cache of a Sonic Wall running one of the above firmwares has a 20 minute life time. This bypasses all rule sets on the firewall. There is no logging of Successful ARP requests or replies, so this type of IP enumeration can go unnoticed. If the SonicWall does not have the requested IP in its ARP cache and the IP is not alive on the LAN side of the firewall there will be an entry in the LOG stating that there was an ARP timeout with a source IP of and a destination IP of the IP requested.

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