Class: Brakeman::CheckWeakHash

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

Constant Summary collapse

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

Instance Method Summary collapse

Instance Method Details

#hashing_password?(call) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/brakeman/checks/check_weak_hash.rb', line 111

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 125

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

  message = msg("Weak hashing algorithm used")

  case call.target.last
  when :MD5
    message << ": " << msg_lit("MD5")
  when :SHA1
    message << ": " << msg_lit("SHA1")
  end

  warn :result => result,
    :warning_type => "Weak Hash",
    :warning_code => :weak_hash_digest,
    :message => message,
    :confidence => confidence,
    :user_input => input,
    :cwe_id => [328]
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]

  message = msg("Weak hashing algorithm used in HMAC")

  case call.third_arg.last
  when :MD5
    message << ": " << msg_lit("MD5")
  when :SHA1
    message << ": " << msg_lit("SHA1")
  end

  warn :result => result,
    :warning_type => "Weak Hash",
    :warning_code => :weak_hash_hmac,
    :message => message,
    :confidence => :medium,
    :cwe_id => [328]
end

#process_ivar(exp) ⇒ Object 



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# File 'lib/brakeman/checks/check_weak_hash.rb', line 135

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 143

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 82

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 => msg("Weak hashing algorithm used: ", msg_lit(alg)),
        :confidence => :medium,
        :cwe_id => [328]
    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 101

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

  nil
end