Class: Brakeman::CheckWeakHash

Inherits:
BaseCheck show all
Defined in:
lib/brakeman/checks/check_weak_hash.rb

Constant Summary collapse

DIGEST_CALLS = 
[:base64digest, :digest, :hexdigest, :new]

Constants inherited from BaseCheck

BaseCheck::CONFIDENCE

Constants included from Util

Util::ALL_COOKIES, Util::ALL_PARAMETERS, Util::COOKIES, Util::COOKIES_SEXP, Util::PARAMETERS, Util::PARAMS_SEXP, Util::PATH_PARAMETERS, Util::QUERY_PARAMETERS, Util::REQUEST_COOKIES, Util::REQUEST_ENV, Util::REQUEST_PARAMETERS, Util::REQUEST_PARAMS, Util::SESSION, Util::SESSION_SEXP

Constants inherited from SexpProcessor

SexpProcessor::VERSION

Instance Attribute Summary

Attributes inherited from BaseCheck

#tracker, #warnings

Attributes inherited from SexpProcessor

#context, #env, #expected

Instance Method Summary collapse

Methods inherited from BaseCheck

#add_result, inherited, #initialize, #process_cookies, #process_default, #process_dstr, #process_if, #process_params

Methods included from Util

#array?, #block?, #call?, #camelize, #class_name, #constant?, #contains_class?, #context_for, #cookies?, #false?, #file_by_name, #file_for, #github_url, #hash?, #hash_access, #hash_insert, #hash_iterate, #integer?, #make_call, #node_type?, #number?, #params?, #pluralize, #rails_version, #regexp?, #relative_path, #request_env?, #request_value?, #result?, #set_env_defaults, #sexp?, #string?, #string_interp?, #symbol?, #table_to_csv, #template_path_to_name, #true?, #truncate_table, #underscore

Methods included from ProcessorHelper

#current_file_name, #process_all, #process_all!, #process_call_args, #process_call_defn?, #process_class, #process_module

Methods inherited from SexpProcessor

#in_context, #initialize, #process, processors, #scope

Constructor Details

This class inherits a constructor from Brakeman::BaseCheck

Instance Method Details

#hashing_password?(call) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/brakeman/checks/check_weak_hash.rb', line 109

def hashing_password? call
  call.each_arg do |arg|
    @has_password = false

    process arg

    if @has_password
      return @has_password
    end
  end

  nil
end

#process_call(exp) ⇒ Object 



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# File 'lib/brakeman/checks/check_weak_hash.rb', line 123

def process_call exp
  if exp.method == :password
    @has_password = exp
  else
    process_default exp
  end

  exp
end

#process_hash_result(result) ⇒ Object 



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# File 'lib/brakeman/checks/check_weak_hash.rb', line 24

def process_hash_result result
  return unless original? result

  input = nil
  call = result[:call]

  if DIGEST_CALLS.include? call.method
    if input = user_input_as_arg?(call)
      confidence = :high
    elsif input = hashing_password?(call)
      confidence = :high
    else
      confidence = :medium
    end
  else
    confidence = :medium
  end


  alg = case call.target.last
        when :MD5
         " (MD5)"
         when :SHA1
          " (SHA1)"
        else
          ""
        end

  warn :result => result,
    :warning_type => "Weak Hash",
    :warning_code => :weak_hash_digest,
    :message => "Weak hashing algorithm#{alg} used",
    :confidence => confidence,
    :user_input => input
end

#process_hmac_result(result) ⇒ Object 



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# File 'lib/brakeman/checks/check_weak_hash.rb', line 60

def process_hmac_result result
  return unless original? result

  call = result[:call]

  alg = case call.third_arg.last
         when :MD5
           'MD5'
         when :SHA1
           'SHA1'
         else
           return
         end

  warn :result => result,
    :warning_type => "Weak Hash",
    :warning_code => :weak_hash_hmac,
    :message => "Weak hashing algorithm (#{alg}) used in HMAC",
    :confidence => :medium
end

#process_ivar(exp) ⇒ Object 



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# File 'lib/brakeman/checks/check_weak_hash.rb', line 133

def process_ivar exp
  if exp.value == :@password
    @has_password = exp
  end

  exp
end

#process_lvar(exp) ⇒ Object 



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# File 'lib/brakeman/checks/check_weak_hash.rb', line 141

def process_lvar exp
  if exp.value == :password
    @has_password = exp
  end

  exp
end

#process_openssl_result(result) ⇒ Object 



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# File 'lib/brakeman/checks/check_weak_hash.rb', line 81

def process_openssl_result result
  return unless original? result

  arg = result[:call].first_arg

  if string? arg
    alg = arg.value.upcase

    if alg == 'MD5' or alg == 'SHA1'
      warn :result => result,
        :warning_type => "Weak Hash",
        :warning_code => :weak_hash_digest,
        :message => "Weak hashing algorithm (#{alg}) used",
        :confidence => :medium
    end
  end
end

#run_check ⇒ Object 



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# File 'lib/brakeman/checks/check_weak_hash.rb', line 10

def run_check
  tracker.find_call(:targets => [:'Digest::MD5', :'Digest::SHA1', :'OpenSSL::Digest::MD5', :'OpenSSL::Digest::SHA1'], :nested => true).each do |result|
    process_hash_result result
  end

  tracker.find_call(:target => :'Digest::HMAC', :methods => [:new, :hexdigest], :nested => true).each do |result|
    process_hmac_result result
  end

  tracker.find_call(:targets => [:'OpenSSL::Digest::Digest', :'OpenSSL::Digest'], :method => :new).each do |result|
    process_openssl_result result
  end
end

#user_input_as_arg?(call) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/brakeman/checks/check_weak_hash.rb', line 99

def user_input_as_arg? call
  call.each_arg do |arg|
    if input = include_user_input?(arg)
      return input
    end
  end

  nil
end