metasploit-framework/modules/auxiliary/scanner/ntp/ntp_monlist.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::Auxiliary::Report
include Msf::Exploit::Remote::Udp
include Msf::Auxiliary::UDPScanner
include Msf::Auxiliary::NTP
include Msf::Auxiliary::DRDoS
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def initialize
super(
'Name' => 'NTP Monitor List Scanner',
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'Description' => %q{
This module identifies NTP servers which permit "monlist" queries and
obtains the recent clients list. The monlist feature allows remote
attackers to cause a denial of service (traffic amplification)
via spoofed requests. The more clients there are in the list, the
greater the amplification.
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},
'References' =>
[
['CVE', '2013-5211'],
['URL', 'https://www.us-cert.gov/ncas/alerts/TA14-013A'],
['URL', 'http://support.ntp.org/bin/view/Main/SecurityNotice'],
['URL', 'http://nmap.org/nsedoc/scripts/ntp-monlist.html'],
],
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'Author' => 'hdm',
'License' => MSF_LICENSE
)
register_options(
[
OptInt.new('RETRY', [false, "Number of tries to query the NTP server", 3]),
OptBool.new('SHOW_LIST', [false, 'Show the recent clients list', false])
])
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register_advanced_options(
[
OptBool.new('StoreNTPClients', [true, 'Store NTP clients as host records in the database', false])
])
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end
# Called for each response packet
def scanner_process(data, shost, sport)
@results[shost] ||= { messages: [], peers: [] }
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@results[shost][:messages] << Rex::Proto::NTP::NTPPrivate.new.read(data).to_binary_s
@results[shost][:peers] << extract_peer_tuples(data)
end
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# Called before the scan block
def scanner_prescan(batch)
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@results = {}
@aliases = {}
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@probe = Rex::Proto::NTP.ntp_private(datastore['VERSION'], datastore['IMPLEMENTATION'], 42, "\0" * 40).to_binary_s
end
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# Called after the scan block
def scanner_postscan(batch)
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@results.keys.each do |k|
response_map = { @probe => @results[k][:messages] }
peer = "#{k}:#{rport}"
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# TODO: check to see if any of the responses are actually NTP before reporting
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report_service(
:host => k,
:proto => 'udp',
:port => rport,
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:name => 'ntp'
)
peers = @results[k][:peers].flatten(1)
unless peers.empty?
print_good("#{peer} NTP monlist request permitted (#{peers.length} entries)")
# store the peers found from the monlist
report_note(
:host => k,
:proto => 'udp',
:port => rport,
:type => 'ntp.monlist',
:data => {:monlist => peers}
)
# print out peers if desired
if datastore['SHOW_LIST']
peers.each do |ntp_peer|
print_status("#{peer} #{ntp_peer}")
end
end
# store any aliases for our target
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report_note(
:host => k,
:proto => 'udp',
:port => rport,
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:type => 'ntp.addresses',
:data => {:addresses => peers.map { |p| p.last }.sort.uniq }
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)
if (datastore['StoreNTPClients'])
print_status("#{peer} Storing #{peers.length} NTP client hosts in the database...")
peers.each do |r|
maddr,mport,mserv = r
next if maddr == '127.0.0.1' # some NTP servers peer with themselves..., but we can't store loopback
report_note(
:host => maddr,
:type => 'ntp.client.history',
:data => {
:address => maddr,
:port => mport,
:server => mserv
}
)
end
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end
end
vulnerable, proof = prove_amplification(response_map)
what = 'NTP Mode 7 monlist DRDoS (CVE-2013-5211)'
if vulnerable
print_good("#{peer} - Vulnerable to #{what}: #{proof}")
report_vuln({
:host => k,
:port => rport,
:proto => 'udp',
:name => what,
:refs => self.references
})
else
vprint_status("#{peer} - Not vulnerable to #{what}: #{proof}")
end
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end
end
# Examine the monlist reponse +data+ and extract all peer tuples (saddd, dport, daddr)
def extract_peer_tuples(data)
return [] if data.length < 76
# NTP headers 8 bytes
ntp_flags, ntp_auth, ntp_vers, ntp_code = data.slice!(0,4).unpack('C*')
pcnt, plen = data.slice!(0,4).unpack('nn')
return [] if plen != 72
idx = 0
peer_tuples = []
1.upto(pcnt) do
# u_int32 firsttime; /* first time we received a packet */
# u_int32 lasttime; /* last packet from this host */
# u_int32 restr; /* restrict bits (was named lastdrop) */
# u_int32 count; /* count of packets received */
# u_int32 addr; /* host address V4 style */
# u_int32 daddr; /* destination host address */
# u_int32 flags; /* flags about destination */
# u_short port; /* port number of last reception */
_,_,_,_,saddr,daddr,_,dport = data[idx, 30].unpack("NNNNNNNn")
peer_tuples << [ Rex::Socket.addr_itoa(saddr), dport, Rex::Socket.addr_itoa(daddr) ]
idx += plen
end
peer_tuples
end
end