Netware - SMB Remote Stack Overflow (PoC)







Stratsec Security Advisory: SS-2010-006 

Title:           Netware SMB Remote Stack Overflow 
Version:         1.0
Issue type:      Stack Overflow
Affected vendor: Novell
Release date:    17/06/2010
Discovered by:   Laurent Gaffié
Issue status:    Patch available



A vulnerability exists in the Netware CIFS.NLM driver which allows an attacker 
to trigger a kernel stack overflow by sending a specific 'Sessions Setup AndX' 
query. Successful exploitation of this issue will result in remote code 
execution with kernel privileges. Failed attempts may result in a remote denial
of service.

The Server Message Block (SMB) protocol, also known as Common Internet File 
System (CIFS) acts as an application-layer protocol to provide shared access
to files, printers and Inter-Process Communication (IPC). It is also a transport
for Distributed Computing Environment / Remote Procedure Call (DCE / RPC) 
operations.After negotiating a SMB communication the client sends a 
'Session Setup AndX' packet to negotiate a session, to be able to connect on a
specific share. By sending a specially crafted request packet containing a long
'AccountName' value, it is possible trigger a kernel stack overflow.


A remote attacker may be able to remotely execute code with kernel privileges
on affected Netware systems. Failed attempts will result in a denial of service.

Affected products

Netware version 6.5 SP8 and prior.

Proof of concept

import sys,socket
from socket import *

if len(sys.argv)<=1:    
 sys.exit('usage: python IP_ADDR')

host = sys.argv[1],139
payload = "A" * 200



## chained Session Setup Andx, tree connect command, field = username, basic stack overflow.

s = socket(AF_INET, SOCK_STREAM)
print "done !"


Apply NSS update located at: 

This patch has not been verified by stratsec.

Response timeline

* 07/02/2010 - Issue discovered.
* 10/02/2010 - Vendor notified.
* 10/02/2010 - Vendor acknowledged receipt of advisory.
* 11/02/2010 - Vendor confirmed issue presence.
* 16/06/2010 - Patch released by vendor.
* 17/06/2010 - stratsec advisory published.


* Vendor advisory:


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