Here we go again. All Windows versions (NT4,W2k,W2k3) in standard
install are affected. No IIS or other packages needed. Bug is in
basic Windows functionality and fully remotely exploitable.

I recommend everybody to inform their [housing] customers immediatly
to install the hotfix right now.

This bug has the potential to make code red, nimda and sql-slammer
look like dwarfs in comparison if a worm is being launched using
this exploit.

-- 
Andre
--- Begin Message ---
http://www.microsoft.com/technet/security/bulletin/MS03-026.asp

Buffer Overrun In RPC Interface Could Allow Code Execution (823980)

Originally posted: July 16, 2003

Summary

Who should read this bulletin: Users running Microsoft � Windows � 

Impact of vulnerability: Run code of attacker's choice

Maximum Severity Rating: Critical

Recommendation: Systems administrators should apply the patch immediately

End User Bulletin: An end user version of this bulletin is available at: 

http://www.microsoft.com/security/security_bulletins/ms03-026.asp.

Affected Software: 
- Microsoft Windows NT� 4.0 
- Microsoft Windows NT 4.0 Terminal Services Edition 
- Microsoft Windows 2000 
- Microsoft Windows XP 
- Microsoft Windows Server(tm) 2003 Not Affected Software:
- Microsoft Windows Millennium Edition</ul

Technical description: 

Remote Procedure Call (RPC) is a protocol used by the Windows operating system. RPC 
provides an inter-process communication mechanism that allows a program running on one 
computer to seamlessly execute code on a remote system. The protocol itself is derived 
from the Open Software Foundation (OSF) RPC protocol, but with the addition of some 
Microsoft specific extensions. 

There is a vulnerability in the part of RPC that deals with message exchange over 
TCP/IP. The failure results because of incorrect handling of malformed messages. This 
particular vulnerability affects a Distributed Component Object Model (DCOM) interface 
with RPC, which listens on TCP/IP port 135. This interface handles DCOM object 
activation requests that are sent by client machines (such as Universal Naming 
Convention (UNC) paths) to the server. An attacker who successfully exploited this 
vulnerability would be able to run code with Local System privileges on an affected 
system. The attacker would be able to take any action on the system, including 
installing programs, viewing changing or deleting data, or creating new accounts with 
full privileges.

To exploit this vulnerability, an attacker would need to send a specially formed 
request to the remote computer on port 135. 

Mitigating factors:
- To exploit this vulnerability, the attacker would require the ability to send a 
specially crafted request to port 135 on the remote machine. For intranet 
environments, this port would normally be accessible, but for Internet connected 
machines, the port 135 would normally be blocked by a firewall. In the case where this 
port is not blocked, or in an intranet configuration, the attacker would not require 
any additional privileges. 
- Best practices recommend blocking all TCP/IP ports that are not actually being used. 
For this reason, most machines attached to the Internet should have port 135 blocked. 
RPC over TCP is not intended to be used in hostile environments such as the Internet. 
More robust protocols such as RPC over HTTP are provided for hostile environments. 

To learn more about securing RPC for client and server please refer to 
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/rpc/rpc/writing_a_secure_rpc_client_or_server.asp.
 

To learn more about the ports used by RPC, please refer to: 
http://www.microsoft.com/technet/prodtechnol/windows2000serv/reskit/tcpip/part4/tcpappc.asp



Vulnerability identifier: CAN-2003-0352



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Cheers,
Russ - Surgeon General of TruSecure Corporation/NTBugtraq Editor

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