Exemplo n.º 1
0
def set_preference(wrapper, arguments, traverser):
    """Tests set preference calls for non-root preferences branches against
    dangerous values."""

    parent = getattr(wrapper, "parent")
    if not (arguments and parent and parent.is_global and
            parent.value.get("preference_branch")):
        return

    arg = traverser._traverse_node(arguments[0])
    if arg.is_literal():
        pref = (parent.value["preference_branch"] +
                actions._get_as_str(arg))

        msg = actions.test_preference(pref)
        if msg:
            kw = {"err_id": ("testcases_javascript_actions",
                             "_call_expression", "called_set_preference"),
                  "warning": "Attempt to set a dangerous preference"}
            if isinstance(msg, dict):
                kw.update(msg)
            else:
                kw["description"] = msg

            traverser.warning(**kw)
def PageMod(args, traverser, node, wrapper):
    """
    This is the function that is called in Jetpack to modify the contents of a
    page with a "content script". This function needs to analyze he first
    parameter. If it is an object and if that object contains a "contentScript"
    string, that string needs to be passed to the validator.testcases.scripting
    library for testing as its own JS script file.
    """

    if not args:
        return

    pm_properties = traverser._traverse_node(args[0])
    if not pm_properties.has_property("contentScript"):
        return

    content_script = pm_properties.get(traverser, "contentScript")
    if not content_script.is_literal():
        return
    content_script = actions._get_as_str(content_script.get_literal_value())
    if not content_script.strip():
        return

    import validator.testcases.scripting as sub_scripting
    sub_scripting.test_js_file(
            traverser.err, traverser.filename, content_script,
            line=traverser.line, context=traverser.context)
Exemplo n.º 3
0
def set_preference(wrapper, arguments, traverser):
    """Tests set preference calls for non-root preferences branches against
    dangerous values."""

    if len(arguments) < 1:
        return

    parent = getattr(wrapper, 'parent', None)
    arg = traverser._traverse_node(arguments[0])
    if arg.is_literal():
        pref = actions._get_as_str(arg)

        # If we're being called on a preference branch other than the root,
        # prepend its branch name to the passed preference name.
        if (parent and parent.is_global
                and parent.value.get('preference_branch')):
            pref = parent.value['preference_branch'] + pref
        else:
            drop_pref_messages(arg)

        kw = {
            'err_id': ('testcases_javascript_actions', '_call_expression',
                       'called_set_preference'),
            'warning':
            'Attempt to set a dangerous preference'
        }

        # Local import to prevent import loop.
        from validator.testcases.regex import validate_pref
        validate_pref(pref, traverser, kw, wrapper=arg)
Exemplo n.º 4
0
def set_contentScript(value, traverser):
    """Warns when values are assigned to the `contentScript` properties,
    which are essentially the same as calling `eval`."""

    if value.is_literal():
        content_script = actions._get_as_str(value)

        # Avoid import loop.
        from validator.testcases.scripting import test_js_file
        test_js_file(traverser.err,
                     traverser.filename,
                     content_script,
                     line=traverser.line,
                     context=traverser.context)
    else:
        traverser.warning(
            err_id=('testcases_javascript_instanceproperties', 'contentScript',
                    'set_non_literal'),
            warning='`contentScript` properties should not be used',
            description='Creating content scripts from dynamic values '
            'is dangerous and error-prone. Please use a separate '
            'JavaScript file, along with the '
            '`contentScriptFile` property instead.',
            signing_help='Please do not use the `contentScript` property '
            'in any add-ons submitted for automated signing.',
            signing_severity='high')
Exemplo n.º 5
0
def PageMod(args, traverser, node, wrapper):
    """
    This is the function that is called in Jetpack to modify the contents of a
    page with a "content script". This function needs to analyze he first
    parameter. If it is an object and if that object contains a "contentScript"
    string, that string needs to be passed to the validator.testcases.scripting
    library for testing as its own JS script file.
    """

    if not args:
        return

    pm_properties = traverser._traverse_node(args[0])
    if not pm_properties.has_property("contentScript"):
        return

    content_script = pm_properties.get(traverser, "contentScript")
    if not content_script.is_literal():
        return
    content_script = actions._get_as_str(content_script.get_literal_value())
    if not content_script.strip():
        return

    import validator.testcases.scripting as sub_scripting
    sub_scripting.test_js_file(
        traverser.err, traverser.filename, content_script,
        line=traverser.line, context=traverser.context)
Exemplo n.º 6
0
def set_preference(wrapper, arguments, traverser):
    """Tests set preference calls for non-root preferences branches against
    dangerous values."""

    if len(arguments) < 1:
        return

    parent = getattr(wrapper, 'parent', None)
    arg = traverser._traverse_node(arguments[0])
    if arg.is_literal():
        pref = actions._get_as_str(arg)

        # If we're being called on a preference branch other than the root,
        # prepend its branch name to the passed preference name.
        if (parent and parent.is_global and
                parent.value.get('preference_branch')):
            pref = parent.value['preference_branch'] + pref
        else:
            drop_pref_messages(arg)

        kw = {'err_id': ('testcases_javascript_actions',
                         '_call_expression', 'called_set_preference'),
              'warning': 'Attempt to set a dangerous preference'}

        # Local import to prevent import loop.
        from validator.testcases.regex import validate_pref
        validate_pref(pref, traverser, kw, wrapper=arg)
Exemplo n.º 7
0
def createElement(args, traverser, node, wrapper):
    """Handles createElement calls"""

    if not args:
        return

    simple_args = map(traverser._traverse_node, args)

    first_as_str = actions._get_as_str(simple_args[0].get_literal_value())
    if first_as_str.lower() == u'script':
        _create_script_tag(traverser)
    elif not simple_args[0].is_literal():
        _create_variable_element(traverser)
Exemplo n.º 8
0
def create_preference_branch(arguments, traverser, node, wrapper):
    """Creates a preference branch, which can be used for testing composed
    preference names."""

    if arguments:
        arg = traverser._traverse_node(arguments[0])
        if arg.is_literal():
            # Avoid import loop
            from predefinedentities import build_quick_xpcom
            res = build_quick_xpcom('createInstance', 'nsIPrefBranch',
                                    traverser, wrapper=True)
            res.value['preference_branch'] = actions._get_as_str(arg)
            return res
Exemplo n.º 9
0
def create_preference_branch(arguments, traverser, node, wrapper):
    """Creates a preference branch, which can be used for testing composed
    preference names."""

    if arguments:
        arg = traverser._traverse_node(arguments[0])
        if arg.is_literal():
            # Avoid import loop
            from predefinedentities import build_quick_xpcom
            res = build_quick_xpcom('createInstance', 'nsIPrefBranch',
                                    traverser, wrapper=True)
            res.value['preference_branch'] = actions._get_as_str(arg)
            return res
Exemplo n.º 10
0
def createElementNS(args, traverser, node, wrapper):
    """Handles createElementNS calls"""

    if not args or len(args) < 2:
        return

    simple_args = map(traverser._traverse_node, args)

    second_as_str = actions._get_as_str(simple_args[1].get_literal_value())
    if 'script' in second_as_str.lower():
        _create_script_tag(traverser)
    elif not simple_args[1].is_literal():
        _create_variable_element(traverser)
Exemplo n.º 11
0
def createElement(args, traverser, node, wrapper):
    """Handles createElement calls"""

    if not args:
        return

    simple_args = map(traverser._traverse_node, args)

    first_as_str = actions._get_as_str(simple_args[0].get_literal_value())
    if first_as_str.lower() == u"script":
        _create_script_tag(traverser)
    elif not simple_args[0].is_literal():
        _create_variable_element(traverser)
Exemplo n.º 12
0
def createElementNS(args, traverser, node, wrapper):
    """Handles createElementNS calls"""

    if not args or len(args) < 2:
        return

    simple_args = map(traverser._traverse_node, args)

    second_as_str = actions._get_as_str(simple_args[1].get_literal_value())
    if "script" in second_as_str.lower():
        _create_script_tag(traverser)
    elif not simple_args[1].is_literal():
        _create_variable_element(traverser)
Exemplo n.º 13
0
def setAttribute(args, traverser, node, wrapper):
    """This ensures that setAttribute calls don't set on* attributes"""

    if not args:
        return

    simple_args = [traverser._traverse_node(a) for a in args]

    first_as_str = actions._get_as_str(simple_args[0].get_literal_value())
    if first_as_str.lower().startswith("on"):
        warn(traverser.err,
             filename=traverser.filename,
             line=traverser.line,
             column=traverser.position,
             context=traverser.context,
             violation_type="setAttribute-on")
Exemplo n.º 14
0
def setAttribute(args, traverser, node, wrapper):
    """This ensures that setAttribute calls don't set on* attributes"""

    if not args:
        return

    simple_args = [traverser._traverse_node(a) for a in args]

    first_as_str = actions._get_as_str(simple_args[0].get_literal_value())
    if first_as_str.lower().startswith("on"):
        warn(traverser.err,
             filename=traverser.filename,
             line=traverser.line,
             column=traverser.position,
             context=traverser.context,
             violation_type="setAttribute-on")
Exemplo n.º 15
0
def setAttribute(args, traverser, node, wrapper):
    """This ensures that setAttribute calls don't set on* attributes"""

    if not args:
        return

    simple_args = [traverser._traverse_node(a) for a in args]

    first_as_str = actions._get_as_str(simple_args[0].get_literal_value())
    if first_as_str.lower().startswith("on"):
        traverser.warning(
            err_id=("testcases_javascript_instanceactions", "setAttribute",
                    "setting_on*"),
            warning="on* attribute being set using setAttribute",
            description="To prevent vulnerabilities, event handlers (like "
                        "'onclick' and 'onhover') should always be defined "
                        "using addEventListener.",
            signing_severity="medium")
Exemplo n.º 16
0
def setAttribute(args, traverser, node, wrapper):
    """This ensures that setAttribute calls don't set on* attributes"""

    if not args:
        return

    simple_args = [traverser._traverse_node(a) for a in args]

    first_as_str = actions._get_as_str(simple_args[0].get_literal_value())
    if first_as_str.lower().startswith("on"):
        traverser.err.notice(
            err_id=("testcases_javascript_instanceactions", "setAttribute",
                    "setting_on*"),
            notice="on* attribute being set using setAttribute",
            description="To prevent vulnerabilities, event handlers (like "
                        "'onclick' and 'onhover') should always be defined "
                        "using addEventListener.",
            filename=traverser.filename,
            line=traverser.line,
            column=traverser.position,
            context=traverser.context)
Exemplo n.º 17
0
def setAttribute(args, traverser, node):
    """This ensures that setAttribute calls don't set on* attributes"""

    if not args:
        return

    simple_args = [traverser._traverse_node(a) for a in args]

    first_as_str = actions._get_as_str(simple_args[0].get_literal_value())
    if first_as_str.lower().startswith("on"):
        traverser.err.notice(
            err_id=("testcases_javascript_instanceactions", "setAttribute",
                        "setting_on*"),
            notice="on* attribute being set using setAttribute",
            description="To prevent vulnerabilities, event handlers (like "
                        "'onclick' and 'onhover') should always be defined "
                        "using addEventListener.",
            filename=traverser.filename,
            line=traverser.line,
            column=traverser.position,
            context=traverser.context)
Exemplo n.º 18
0
def set_contentScript(value, traverser):
    """Warns when values are assigned to the `contentScript` properties,
    which are essentially the same as calling `eval`."""

    if value.is_literal():
        content_script = actions._get_as_str(value)

        # Avoid import loop.
        from validator.testcases.scripting import test_js_file
        test_js_file(
            traverser.err, traverser.filename, content_script,
            line=traverser.line, context=traverser.context)
    else:
        traverser.warning(
            err_id=("testcases_javascript_instanceproperties",
                    "contentScript", "set_non_literal"),
            warning="`contentScript` properties should not be used",
            description="Creating content scripts from dynamic values "
                        "is dangerous and error-prone. Please use a separate "
                        "JavaScript file, along with the "
                        "`contentScriptFile` property instead.",
            signing_severity="high")
Exemplo n.º 19
0
def setAttribute(args, traverser, node, wrapper):
    """This ensures that setAttribute calls don't set on* attributes"""

    if not args:
        return

    simple_args = [traverser._traverse_node(a) for a in args]

    first_as_str = actions._get_as_str(simple_args[0].get_literal_value())
    if first_as_str.lower().startswith('on'):
        traverser.warning(
            err_id=('testcases_javascript_instanceactions', 'setAttribute',
                    'setting_on*'),
            warning='on* attribute being set using setAttribute',
            description='To prevent vulnerabilities, event handlers (like '
                        "'onclick' and 'onhover') should always be defined "
                        'using addEventListener.',
            signing_help='Please use `addEventListener` any place you might '
                         'otherwise create event listener attributes. Event '
                         'listener attributes will not be accepted in add-ons '
                         'submitted for automated signing in any instance '
                         'where they may be reasonably avoided.',
            signing_severity='medium')
Exemplo n.º 20
0
def setAttribute(args, traverser, node, wrapper):
    """This ensures that setAttribute calls don't set on* attributes"""

    if not args:
        return

    simple_args = [traverser._traverse_node(a) for a in args]

    first_as_str = actions._get_as_str(simple_args[0].get_literal_value())
    if first_as_str.lower().startswith('on'):
        traverser.warning(
            err_id=('testcases_javascript_instanceactions', 'setAttribute',
                    'setting_on*'),
            warning='on* attribute being set using setAttribute',
            description='To prevent vulnerabilities, event handlers (like '
            "'onclick' and 'onhover') should always be defined "
            'using addEventListener.',
            signing_help='Please use `addEventListener` any place you might '
            'otherwise create event listener attributes. Event '
            'listener attributes will not be accepted in add-ons '
            'submitted for automated signing in any instance '
            'where they may be reasonably avoided.',
            signing_severity='medium')
def set_contentScript(value, traverser):
    """Warns when values are assigned to the `contentScript` properties,
    which are essentially the same as calling `eval`."""

    if value.is_literal():
        content_script = actions._get_as_str(value)

        # Avoid import loop.
        from validator.testcases.scripting import test_js_file
        test_js_file(
            traverser.err, traverser.filename, content_script,
            line=traverser.line, context=traverser.context)
    else:
        traverser.warning(
            err_id=('testcases_javascript_instanceproperties',
                    'contentScript', 'set_non_literal'),
            warning='`contentScript` properties should not be used',
            description='Creating content scripts from dynamic values '
                        'is dangerous and error-prone. Please use a separate '
                        'JavaScript file, along with the '
                        '`contentScriptFile` property instead.',
            signing_help='Please do not use the `contentScript` property '
                         'in any add-ons submitted for automated signing.',
            signing_severity='high')
Exemplo n.º 22
0
 def _process_literal(type_, literal):
     if type_ == "string":
         return actions._get_as_str(literal)
     elif type_ == "num":
         return actions._get_as_num(literal)
     return literal
Exemplo n.º 23
0
 "value":
     {u"classes":
          {"xpcom_wildcard": True,
           "value":
               {u"createInstance":
                   {"return": xpcom_const("createInstance")},
                u"getService":
                   {"return": xpcom_const("getService")}}},
      "utils":
          {"value": {u"evalInSandbox":
                         {"dangerous": True},
                     u"import":
                         {"dangerous":
                              lambda a, t, e:
                                a and
                                _get_as_str(t(a[0]).get_literal_value())
                                    .count("ctypes.jsm")}}},
      u"interfaces":
          {"value": {u"nsIXMLHttpRequest":
                        {"xpcom_map":
                             lambda:
                                GLOBAL_ENTITIES["XMLHttpRequest"]},
                     u"nsIAccessibleRetrieval":
                        {"xpcom_map":
                             lambda:
                                INTERFACES["nsIAccessibleRetrieval"]},
                     u"nsIBrowserSearchService":
                        {"xpcom_map":
                             lambda:
                                INTERFACES["nsIBrowserSearchService"]},
                     u"nsICategoryManager":
                        {"xpcom_map":
Exemplo n.º 24
0
                       {"value":
                            lambda t: build_quick_xpcom("getService",
                                                        "nsIWindowWatcher",
                                                        t)}}},

    u"document":
        {"value":
             {u"title":
                  {"overwriteable": True,
                   "readonly": False},
              u"defaultView":
                  {"value": lambda t: {"value": GLOBAL_ENTITIES}},
              u"createElement":
                  {"dangerous":
                       lambda a, t, e:
                           not a or _get_as_str(t(a[0])).lower() == "script"},
              u"createElementNS":
                  {"dangerous":
                       lambda a, t, e:
                           not a or _get_as_str(t(a[0])).lower() == "script"},
              u"getSelection":
                  {"return": call_definitions.document_getSelection},
              u"loadOverlay":
                  {"dangerous":
                       lambda a, t, e:
                           not a or not _get_as_str(t(a[0])).lower()
                               .startswith(("chrome:", "resource:"))},
              u"xmlEncoding": entity("document.xmlEncoding"),
              u"xmlVersion": entity("document.xmlVersion"),
              u"xmlStandalone": entity("document.xmlStandalone")}},
Exemplo n.º 25
0
def string_global(wrapper, arguments, traverser):
    if not arguments:
        return JSWrapper('', traverser=traverser)
    arg = traverser._traverse_node(arguments[0])
    value = actions._get_as_str(arg.get_literal_value())
    return JSWrapper(value, traverser=traverser)
Exemplo n.º 26
0
 def _process_literal(type_, literal):
     if type_ == "string":
         return actions._get_as_str(literal)
     elif type_ == "num":
         return actions._get_as_num(literal)
     return literal
        }
    },
    u'document': {
        'value': {
            u'title': {
                'overwriteable': True,
                'readonly': False
            },
            u'defaultView': {
                'value': lambda t: {
                    'value': GLOBAL_ENTITIES
                }
            },
            u'loadOverlay': {
                'dangerous':
                lambda a, t, e: not a or not _get_as_str(t(a[0])).lower().
                startswith(('chrome:', 'resource:'))
            },
            u'write': entity('document.write'),
            u'writeln': entity('document.write')
        }
    },

    # The nefariuos timeout brothers!
    u'setTimeout': {
        'dangerous': actions._call_settimeout
    },
    u'setInterval': {
        'dangerous': actions._call_settimeout
    },
    u'require': {
        'dangerous': actions._call_require
Exemplo n.º 28
0
 u"navigator": {"value": {u"wifi": {"dangerous": True}, u"geolocation": {"dangerous": True}}},
 u"Components": {
     "readonly": True,
     "value": {
         u"classes": {
             "xpcom_wildcard": True,
             "value": {
                 u"createInstance": {"return": xpcom_const("createInstance")},
                 u"getService": {"return": xpcom_const("getService")},
             },
         },
         "utils": {
             "value": {
                 u"evalInSandbox": {"dangerous": True},
                 u"import": {
                     "dangerous": lambda a, t, e: a and _get_as_str(t(a[0]).get_literal_value()).count("ctypes.jsm")
                 },
             }
         },
         u"interfaces": {
             "value": {
                 u"nsIXMLHttpRequest": {"xpcom_map": lambda: GLOBAL_ENTITIES["XMLHttpRequest"]},
                 u"nsIAccessibleRetrieval": {"xpcom_map": lambda: INTERFACES["nsIAccessibleRetrieval"]},
                 u"nsICategoryManager": {"xpcom_map": lambda: INTERFACES["nsICategoryManager"]},
                 u"nsIComponentRegistrar": {"xpcom_map": lambda: INTERFACES["nsIComponentRegistrar"]},
                 u"nsIJSON": {"xpcom_map": lambda: INTERFACES["nsIJSON"]},
                 u"nsIImapMailFolderSink": {"xpcom_map": lambda: INTERFACES["nsIImapMailFolderSink"]},
                 u"nsIImapProtocol": {"xpcom_map": lambda: INTERFACES["nsIImapProtocol"]},
                 u"nsIMsgSearchScopeTerm": {"xpcom_map": lambda: INTERFACES["nsIMsgSearchScopeTerm"]},
                 u"nsIMsgThread": {"xpcom_map": lambda: INTERFACES["nsIMsgThread"]},
                 u"nsIObserverService": {"xpcom_map": lambda: INTERFACES["nsIObserverService"]},
Exemplo n.º 29
0
def string_global(wrapper, arguments, traverser):
    if not arguments:
        return JSWrapper('', traverser=traverser)
    arg = traverser._traverse_node(arguments[0])
    value = actions._get_as_str(arg.get_literal_value())
    return JSWrapper(value, traverser=traverser)
Exemplo n.º 30
0
 def _process_literal(type_, literal):
     if type_ == 'string':
         return actions._get_as_str(literal)
     elif type_ == 'num':
         return actions._get_as_num(literal)
     return literal
                         'Any code which makes use of the `ctypes` API '
                         'must undergo manual code review for at least one '
                         'submission.'),
        'signing_severity': 'high'}},

    u'document':
        {'value':
             {u'title':
                  {'overwriteable': True,
                   'readonly': False},
              u'defaultView':
                  {'value': lambda t: {'value': GLOBAL_ENTITIES}},
              u'loadOverlay':
                  {'dangerous':
                       lambda a, t, e:
                           not a or not _get_as_str(t(a[0])).lower()
                               .startswith(('chrome:', 'resource:'))},
              u'write': entity('document.write'),
              u'writeln': entity('document.write')}},

    # The nefariuos timeout brothers!
    u'setTimeout': {'dangerous': actions._call_settimeout},
    u'setInterval': {'dangerous': actions._call_settimeout},

    u'require': {'dangerous': actions._call_require},

    u'encodeURI': {'readonly': True},
    u'decodeURI': {'readonly': True},
    u'encodeURIComponent': {'readonly': True},
    u'decodeURIComponent': {'readonly': True},
    u'escape': {'readonly': True},
    u'unescape': {'readonly': True},
Exemplo n.º 32
0
 def _process_literal(type_, literal):
     if type_ == 'string':
         return actions._get_as_str(literal)
     elif type_ == 'num':
         return actions._get_as_num(literal)
     return literal
Exemplo n.º 33
0
     }
 },
 u"document": {
     "value": {
         u"title": {
             "overwriteable": True,
             "readonly": False
         },
         u"defaultView": {
             "value": lambda t: {
                 "value": GLOBAL_ENTITIES
             }
         },
         u"createElement": {
             "dangerous":
             lambda a, t, e: not a or _get_as_str(t(a[0])).lower() ==
             "script" and "Dynamic creation of script nodes can be "
             "unsafe if contents are not static or are "
             "otherwise unsafe, or if `src` is remote."
         },
         u"createElementNS": {
             "dangerous":
             lambda a, t, e: not a or _get_as_str(t(a[0])).lower() ==
             "script" and "Dynamic creation of script nodes can be "
             "unsafe if contents are not static or are "
             "otherwise unsafe, or if `src` is remote."
         },
         u"getSelection": {
             "return": call_definitions.document_getSelection
         },
         u"loadOverlay": {
Exemplo n.º 34
0
 u"null": {"literal": lambda t: JSWrapper(None, traverser=t)},
 u"Cc": {"readonly": False, "value": lambda t: GLOBAL_ENTITIES["Components"]["value"]["classes"]},
 u"Ci": {"readonly": False, "value": lambda t: GLOBAL_ENTITIES["Components"]["value"]["interfaces"]},
 u"Cu": {"readonly": False, "value": lambda t: GLOBAL_ENTITIES["Components"]["value"]["utils"]},
 u"Services": {
     "value": {
         u"scriptloader": {"dangerous": True},
         u"wm": {"value": lambda t: build_quick_xpcom("getService", "nsIWindowMediator", t)},
         u"ww": {"value": lambda t: build_quick_xpcom("getService", "nsIWindowWatcher", t)},
     }
 },
 u"document": {
     "value": {
         u"title": {"overwriteable": True, "readonly": False},
         u"defaultView": {"value": lambda t: {"value": GLOBAL_ENTITIES}},
         u"createElement": {"dangerous": lambda a, t, e: not a or _get_as_str(t(a[0])).lower() == "script"},
         u"createElementNS": {"dangerous": lambda a, t, e: not a or _get_as_str(t(a[0])).lower() == "script"},
         u"getSelection": {"return": call_definitions.document_getSelection},
         u"loadOverlay": {
             "dangerous": lambda a, t, e: not a
             or not _get_as_str(t(a[0])).lower().startswith(("chrome:", "resource:"))
         },
         u"write": entity("document.write"),
         u"writeln": entity("document.write"),
         u"xmlEncoding": entity("document.xmlEncoding"),
         u"xmlVersion": entity("document.xmlVersion"),
         u"xmlStandalone": entity("document.xmlStandalone"),
     }
 },
 # The nefariuos timeout brothers!
 u"setTimeout": {"dangerous": actions._call_settimeout},
Exemplo n.º 35
0
                                                        t)},
                   u"ww":
                       {"value":
                            lambda t: build_quick_xpcom("getService",
                                                        "nsIWindowWatcher",
                                                        t)}}},

    u"document":
        {"value": {u"title":
                       {"overwriteable": True,
                        "readonly": False},
                   u"createElement":
                       {"dangerous":
                            lambda a, t, e:
                                not a or
                                _get_as_str(t(a[0]).get_literal_value())
                                                .lower() == "script"},
                   u"createElementNS":
                       {"dangerous":
                            lambda a, t, e:
                                not a or
                                _get_as_str(t(a[0]).get_literal_value())
                                                .lower() == "script"},
                   u"loadOverlay":
                       {"dangerous":
                            lambda a, t, e:
                                not a or
                                not _get_as_str(t(a[0]).get_literal_value())
                                        .lower()
                                        .startswith(("chrome:",
                                                     "resource:"))}}},