90 lines
2.5 KiB
Ruby
90 lines
2.5 KiB
Ruby
# -*- coding: binary -*-
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###
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#
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#
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###
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module Msf
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module Util
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#
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# The class provides helper methods for verifying and updating the embedded CachedSize
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# constant within payload modules.
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#
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class PayloadCachedSize
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# Insert a new CachedSize value into the text of a payload module
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#
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# @param data [String] The source code of a payload module
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# @param cached_size [String] The new value for cached_size, which
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# which should be either numeric or the string :dynamic
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# @return [String]
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def self.update_cache_constant(data, cached_size)
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data.
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gsub(/^\s*CachedSize\s*=\s*(\d+|:dynamic).*/, '').
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gsub(/^(module Metasploit\d+)\s*\n/) do |m|
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"#{m.strip}\n\n CachedSize = #{cached_size}\n\n"
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end
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end
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# Insert a new CachedSize value into a payload module file
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#
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# @param mod [Msf::Payload] The class of the payload module to update
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# @param cached_size [String] The new value for cached_size, which
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# which should be either numeric or the string :dynamic
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# @return [void]
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def self.update_cached_size(mod, cached_size)
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mod_data = ""
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::File.open(mod.file_path, 'rb') do |fd|
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mod_data = fd.read(fd.stat.size)
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end
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::File.open(mod.file_path, 'wb') do |fd|
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fd.write update_cache_constant(mod_data, cached_size)
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end
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end
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# Updates the payload module specified with the current CachedSize
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#
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# @param mod [Msf::Payload] The class of the payload module to update
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# @return [void]
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def self.update_module_cached_size(mod)
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update_cached_size(mod, compute_cached_size(mod))
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end
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# Calculates the CachedSize value for a payload module
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#
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# @param mod [Msf::Payload] The class of the payload module to update
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# @return [Fixnum]
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def self.compute_cached_size(mod)
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return ":dynamic" if is_dynamic?(mod)
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return mod.new.size
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end
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# Determines whether a payload generates a static sized output
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#
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# @param mod [Msf::Payload] The class of the payload module to update
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# @param generation_count [Fixnum] The number of iterations to use to
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# verify that the size is static.
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# @return [Fixnum]
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def self.is_dynamic?(mod,generation_count=5)
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[*(1..generation_count)].map{|x| mod.new.size}.uniq.length != 1
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end
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# Determines whether a payload's CachedSize is up to date
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#
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# @param mod [Msf::Payload] The class of the payload module to update
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# @return [Boolean]
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def self.is_cached_size_accurate?(mod)
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return true if mod.dynamic_size?
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return false if mod.cached_size.nil?
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mod.cached_size == mod.new.size
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end
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end
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end
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end
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