This Metasploit module can be used to discover Memcached servers which expose the unrestricted UDP port 11211. A basic “stats” request is executed to check if an amplification attack is possible against a third party.
advisories | CVE-2018-1000115
##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
class MetasploitModule < Msf::Auxiliary
include Msf::Auxiliary::Report
include Msf::Exploit::Capture
include Msf::Auxiliary::UDPScanner
include Msf::Auxiliary::DRDoS
def initialize
super(
'Name' => 'Memcached Stats Amplification Scanner',
'Description' => %q(
This module can be used to discover Memcached servers which expose the
unrestricted UDP port 11211. A basic "stats" request is executed to check
if an amplification attack is possible against a third party.
),
'Author' =>
[
'Marek Majkowski', # Cloudflare blog and base payload
'xistence <xistence[at]0x90.nl>', # Metasploit scanner module
'Jon Hart <[email protected]>', # Metasploit scanner module
],
'License' => MSF_LICENSE,
'DisclosureDate' => 'Feb 27 2018',
'References' =>
[
['URL', 'https://blog.cloudflare.com/memcrashed-major-amplification-attacks-from-port-11211/'],
['CVE', '2018-1000115']
]
)
register_options([
Opt::RPORT(11211)
])
end
def build_probe
# Memcached stats probe, per https://github.com/memcached/memcached/blob/master/doc/protocol.txt
@memcached_probe ||= [
rand(2**16), # random request ID
0, # sequence number
1, # number of datagrams in this sequence
0, # reserved; must be 0
"statsrn"
].pack("nnnna*")
end
def scanner_process(data, shost, sport)
# Check the response data for a "STAT" response
if data =~ /x0dx0aSTATx20/
@results[shost] ||= []
@results[shost] << data
end
end
# Called after the scan block
def scanner_postscan(batch)
@results.keys.each do |host|
response_map = { @memcached_probe => @results[host] }
report_service(
host: host,
proto: 'udp',
port: rport,
name: 'memcached'
)
peer = "#{host}:#{rport}"
vulnerable, proof = prove_amplification(response_map)
what = 'memcached stats amplification'
if vulnerable
print_good("#{peer} - Vulnerable to #{what}: #{proof}")
report_vuln(
host: host,
port: rport,
proto: 'udp',
name: what,
refs: references
)
else
vprint_status("#{peer} - Not vulnerable to #{what}: #{proof}")
end
end
end
end