NetScreen ScreenOS 4.0.3r2 DOS

[Papa loves Mambo <plm () ioerror org>]

There is a vulnerability in NetScreen's latest ScreenOS
that allows a malicious user to create a denial of
service attack remotely.

This has only been confirmed with the following
operating systems and NetScreen hardware.

Microsoft Windows 2000 Professional SP1 and SP2
NetScreen 204 and 208

By modifying the TCP Window size in the registry in W2K
a user can cause a NetScreen 20x running ScreenOS
4.0.3r2 to core dump the ASIC and reboot.

This only affects devices that have management services
such as Web, Telnet, or SSH enabled on an interface.

When a user tries to connect to one of the management
ports with the registry settings below the NetScreen
crashes.

\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
New DWORD Value

Tcp1323Opts
HEX
3

TcpWindowSize
Decimal
131400

Papa Love Mambo Research Group
plm at ioerror.org