296 lines
9.2 KiB
Ruby
296 lines
9.2 KiB
Ruby
module Msf
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require 'msf/core/exploit/tcp'
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###
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#
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# This module exposes methods that may be useful to exploits that deal with
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# servers that speak the telnet protocol.
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#
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###
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module Exploit::Remote::Telnet
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include Exploit::Remote::Tcp
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# Borrowing constants from Ruby's Net::Telnet class (ruby license)
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IAC = 255.chr # "\377" # "\xff" # interpret as command
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DONT = 254.chr # "\376" # "\xfe" # you are not to use option
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DO = 253.chr # "\375" # "\xfd" # please, you use option
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WONT = 252.chr # "\374" # "\xfc" # I won't use option
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WILL = 251.chr # "\373" # "\xfb" # I will use option
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SB = 250.chr # "\372" # "\xfa" # interpret as subnegotiation
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GA = 249.chr # "\371" # "\xf9" # you may reverse the line
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EL = 248.chr # "\370" # "\xf8" # erase the current line
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EC = 247.chr # "\367" # "\xf7" # erase the current character
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AYT = 246.chr # "\366" # "\xf6" # are you there
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AO = 245.chr # "\365" # "\xf5" # abort output--but let prog finish
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IP = 244.chr # "\364" # "\xf4" # interrupt process--permanently
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BREAK = 243.chr # "\363" # "\xf3" # break
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DM = 242.chr # "\362" # "\xf2" # data mark--for connect. cleaning
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NOP = 241.chr # "\361" # "\xf1" # nop
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SE = 240.chr # "\360" # "\xf0" # end sub negotiation
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EOR = 239.chr # "\357" # "\xef" # end of record (transparent mode)
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ABORT = 238.chr # "\356" # "\xee" # Abort process
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SUSP = 237.chr # "\355" # "\xed" # Suspend process
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EOF = 236.chr # "\354" # "\xec" # End of file
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SYNCH = 242.chr # "\362" # "\xf2" # for telfunc calls
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OPT_BINARY = 0.chr # "\000" # "\x00" # Binary Transmission
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OPT_ECHO = 1.chr # "\001" # "\x01" # Echo
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OPT_RCP = 2.chr # "\002" # "\x02" # Reconnection
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OPT_SGA = 3.chr # "\003" # "\x03" # Suppress Go Ahead
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OPT_NAMS = 4.chr # "\004" # "\x04" # Approx Message Size Negotiation
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OPT_STATUS = 5.chr # "\005" # "\x05" # Status
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OPT_TM = 6.chr # "\006" # "\x06" # Timing Mark
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OPT_RCTE = 7.chr # "\a" # "\x07" # Remote Controlled Trans and Echo
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OPT_NAOL = 8.chr # "\010" # "\x08" # Output Line Width
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OPT_NAOP = 9.chr # "\t" # "\x09" # Output Page Size
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OPT_NAOCRD = 10.chr # "\n" # "\x0a" # Output Carriage-Return Disposition
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OPT_NAOHTS = 11.chr # "\v" # "\x0b" # Output Horizontal Tab Stops
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OPT_NAOHTD = 12.chr # "\f" # "\x0c" # Output Horizontal Tab Disposition
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OPT_NAOFFD = 13.chr # "\r" # "\x0d" # Output Formfeed Disposition
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OPT_NAOVTS = 14.chr # "\016" # "\x0e" # Output Vertical Tabstops
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OPT_NAOVTD = 15.chr # "\017" # "\x0f" # Output Vertical Tab Disposition
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OPT_NAOLFD = 16.chr # "\020" # "\x10" # Output Linefeed Disposition
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OPT_XASCII = 17.chr # "\021" # "\x11" # Extended ASCII
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OPT_LOGOUT = 18.chr # "\022" # "\x12" # Logout
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OPT_BM = 19.chr # "\023" # "\x13" # Byte Macro
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OPT_DET = 20.chr # "\024" # "\x14" # Data Entry Terminal
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OPT_SUPDUP = 21.chr # "\025" # "\x15" # SUPDUP
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OPT_SUPDUPOUTPUT = 22.chr # "\026" # "\x16" # SUPDUP Output
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OPT_SNDLOC = 23.chr # "\027" # "\x17" # Send Location
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OPT_TTYPE = 24.chr # "\030" # "\x18" # Terminal Type
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OPT_EOR = 25.chr # "\031" # "\x19" # End of Record
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OPT_TUID = 26.chr # "\032" # "\x1a" # TACACS User Identification
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OPT_OUTMRK = 27.chr # "\e" # "\x1b" # Output Marking
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OPT_TTYLOC = 28.chr # "\034" # "\x1c" # Terminal Location Number
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OPT_3270REGIME = 29.chr # "\035" # "\x1d" # Telnet 3270 Regime
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OPT_X3PAD = 30.chr # "\036" # "\x1e" # X.3 PAD
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OPT_NAWS = 31.chr # "\037" # "\x1f" # Negotiate About Window Size
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OPT_TSPEED = 32.chr # " " # "\x20" # Terminal Speed
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OPT_LFLOW = 33.chr # "!" # "\x21" # Remote Flow Control
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OPT_LINEMODE = 34.chr # "\"" # "\x22" # Linemode
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OPT_XDISPLOC = 35.chr # "#" # "\x23" # X Display Location
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OPT_OLD_ENVIRON = 36.chr # "$" # "\x24" # Environment Option
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OPT_AUTHENTICATION = 37.chr # "%" # "\x25" # Authentication Option
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OPT_ENCRYPT = 38.chr # "&" # "\x26" # Encryption Option
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OPT_NEW_ENVIRON = 39.chr # "'" # "\x27" # New Environment Option
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OPT_EXOPL = 255.chr # "\377" # "\xff" # Extended-Options-List
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NULL = "\000"
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CR = "\015"
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LF = "\012"
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EOL = CR + LF
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#
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# Creates an instance of a Telnet exploit module.
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#
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def initialize(info = {})
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super
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# Register the options that all Telnet exploits may make use of.
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register_options(
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[
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Opt::RHOST,
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Opt::RPORT(23),
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OptString.new('USERNAME', [ false, 'The username to authenticate as' ]),
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OptString.new('PASSWORD', [ false, 'The password for the specified username' ])
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], Msf::Exploit::Remote::Telnet)
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register_advanced_options(
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[
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OptInt.new('TelnetTimeout', [ true, 'The number of seconds to wait for a reply from a Telnet command', 10]),
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OptInt.new('TelnetBannerTimeout', [ true, 'The number of seconds to wait for the initial banner', 25])
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], Msf::Exploit::Remote::Telnet)
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register_autofilter_ports([ 23 ])
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register_autofilter_services(%W{ telnet })
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end
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#
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# This method establishes an Telnet connection to host and port specified by
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# the RHOST and RPORT options, respectively. After connecting, the banner
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# message is read in and stored in the 'banner' attribute. This method has the
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# benefit of handling telnet option negotiation.
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#
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def connect(global = true, verbose = true)
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fd = super(global)
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self.banner = ''
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# Wait for a banner to arrive...
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begin
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Timeout.timeout(datastore['TelnetBannerTimeout']) do
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while(true)
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buff = recv_telnet(fd)
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self.banner << buff if buff
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if(self.banner =~ /login|user|welcome|pass|\$|\#/i)
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break
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end
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end
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end
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rescue ::Timeout::Error
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end
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self.banner.strip!
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# Return the file descriptor to the caller
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fd
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end
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#
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# Handle telnet option negotiation
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#
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def recv_telnet(fd=self.sock, timeout=datastore['TelnetTimeout'])
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data = fd.get_once(-1, timeout.to_i)
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return nil if not data
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# combine CR+NULL into CR
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data.gsub!(/#{CR}#{NULL}/no, CR)
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# combine EOL into "\n"
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data.gsub!(/#{EOL}/no, "\n")
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data.gsub(/#{IAC}(
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[#{IAC}#{AO}#{AYT}#{DM}#{IP}#{NOP}]|
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[#{DO}#{DONT}#{WILL}#{WONT}]
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[#{OPT_BINARY}-#{OPT_NEW_ENVIRON}#{OPT_EXOPL}]|
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#{SB}[^#{IAC}]*#{IAC}#{SE}
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)/xno) do
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m = $1
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if m == IAC
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IAC
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elsif m == AYT
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fd.write("YES" + EOL)
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elsif m[0,1] == DO
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if(m[1,1] == OPT_BINARY)
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fd.write(IAC + WILL + OPT_BINARY)
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else
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fd.write(IAC + WONT + m[1,1])
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end
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''
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elsif m[0,1] == DONT
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fd.write(IAC + WONT + m[1,1])
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''
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elsif m[0,1] == WILL
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if m[1,1] == OPT_BINARY
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fd.write(IAC + DO + OPT_BINARY)
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elsif m[1,1] == OPT_ECHO
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fd.write(IAC + DO + OPT_ECHO)
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elsif m[1,1] == OPT_SGA
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fd.write(IAC + DO + OPT_SGA)
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else
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fd.write(IAC + DONT + m[1,1])
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end
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''
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elsif m[0,1] == WONT
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fd.write(IAC + DONT + m[1,1])
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''
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else
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''
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end
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end
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end
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def user
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datastore["USERNAME"]
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end
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def pass
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datastore["PASSWORD"]
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end
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#
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# Connect and login to the remote telnet server using the credentials
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# that have been supplied in the exploit options.
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#
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def connect_login(global = true, verbose = true)
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telsock = connect(global, verbose)
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if !(user and pass)
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print_status("No username and password were supplied, unable to login")
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return false
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end
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print_status("Authenticating as #{user} with password #{pass}...") if verbose
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res = send_user(user, telsock)
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if (pass)
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print_status("Sending password...") if verbose
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res = send_pass(pass, telsock)
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if (res =~ /fail/i)
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print_status("The server rejected our password") if verbose
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return false
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end
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end
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return telsock
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end
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#
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# This method logs in as the supplied user by transmitting the username
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#
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def send_user(user, nsock = self.sock)
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raw_send("#{user}\r\n", nsock)
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recv_telnet(nsock)
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end
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#
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# This method completes user authentication by sending the supplied password
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#
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def send_pass(pass, nsock = self.sock)
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raw_send("#{pass}\r\n", nsock)
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# Servers send options after a successful login, so we have to do two
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# recv's to catch that and the initial prompt
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resp = recv_telnet(nsock)
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resp = recv_telnet(nsock) if resp.length == 0
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resp
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end
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#
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# This method sends one command with zero or more parameters
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#
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def send_cmd(args, recv = true, nsock = self.sock)
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cmd = args.join(" ") + "\r\n"
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ret = raw_send(cmd, nsock)
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if (recv)
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return recv_telnet(nsock)
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end
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return ret
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end
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#
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# This method transmits a telnet command and does not wait for a response
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#
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def raw_send(cmd, nsock = self.sock)
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nsock.put(cmd)
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end
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##
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#
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# Wrappers for getters
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#
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##
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#
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# Returns the number of seconds to wait for a telnet reply
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#
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def tel_timeout
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(datastore['TelnetTimeout'] || 10).to_i
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end
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protected
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#
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# This attribute holds the banner that was read in after a successful call
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# to connect or connect_login.
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#
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attr_accessor :banner
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end
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end
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