[NT] Windows RPC Service DoS (SPIKE)

From: support@securiteam.com
Date: 10/19/02

From: support@securiteam.com
To: list@securiteam.com
Date: 19 Oct 2002 00:25:38 +0200

The following security advisory is sent to the securiteam mailing list, and can be found at the SecuriTeam web site: http://www.securiteam.com
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  Windows RPC Service DoS (SPIKE)


A security vulnerability in Windows's RPC implementaiton allows remote
attackers to cause it to no longer respond to legitimate requests by
sending it a malformed request. This effectivily allows a remote attacker
to cause a denial of service attack against the Windows operating system.


Vulnerable systems:
 * Windows 2000 SP1-SP3

Remote Windows 2000 machines with port TCP 135 open to the Internet can be
disabled without authentication of any kind. Other versions of Windows may
also be vulnerable.

Technical details:
The vulnerability itself is within the DCE-RPC stack of Windows 2000 and
related OS's. This vulnerability allows anyone who can connect to port 135
TCP to disable the RPC service. Disabling the RPC service causes the
machine to stop responding to new RPC requests, disabling almost all

This is a Denial of Service via a null pointer dereference, and not
exploitable to gain permissions on the remote machine. A proof of concept
is available at <http://www.immunitysec.com/vulnerabilities/>

This proof of concept Linux executable is derived from SPIKE 2.7 source
code. Simply running SPIKE 2.7's msrpcfuzz is also known to replicate this

Block port tcp/135 from network connections. There are also configuration
changes that can make you immune to this attack, but these are not
completely known at this time.


The information has been provided by <mailto:dave@immunitysec.com> Dave


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