Validate patterns when creating Indicators

setup.py

@@ -50,5 +50,6 @@ setup(
         'six',
         'python-dateutil',
         'requests',
+        'stix2-patterns',
     ],
 )

stix2/properties.py

@@ -7,6 +7,8 @@ import uuid
 
 from six import string_types, text_type
 
+from stix2patterns.validator import run_validator
+
 from .base import _STIXBase
 from .exceptions import DictionaryKeyError
 from .utils import get_dict, parse_into_datetime
@@ -370,3 +372,17 @@ class EnumProperty(StringProperty):
         if value not in self.allowed:
             raise ValueError("value '%s' is not valid for this enumeration." % value)
         return self.string_type(value)
+
+
+class PatternProperty(StringProperty):
+
+    def __init__(self, **kwargs):
+        super(PatternProperty, self).__init__(**kwargs)
+
+    def clean(self, value):
+        str_value = super(PatternProperty, self).clean(value)
+        errors = run_validator(str_value)
+        if errors:
+            raise ValueError(str(errors[0]))
+
+        return self.string_type(value)

stix2/sdo.py

@@ -6,8 +6,8 @@ from .base import _STIXBase
 from .common import COMMON_PROPERTIES, KillChainPhase
 from .observables import ObservableProperty
 from .properties import (IDProperty, IntegerProperty, ListProperty,
-                         ReferenceProperty, StringProperty, TimestampProperty,
-                         TypeProperty)
+                         PatternProperty, ReferenceProperty, StringProperty,
+                         TimestampProperty, TypeProperty)
 from .utils import NOW
 
 
@@ -77,7 +77,7 @@ class Indicator(_STIXBase):
         'labels': ListProperty(StringProperty, required=True),
         'name': StringProperty(),
         'description': StringProperty(),
-        'pattern': StringProperty(required=True),
+        'pattern': PatternProperty(required=True),
         'valid_from': TimestampProperty(default=lambda: NOW),
         'valid_until': TimestampProperty(),
         'kill_chain_phases': ListProperty(KillChainPhase),

stix2/test/test_indicator.py

@@ -174,3 +174,23 @@ def test_parse_indicator(data):
     assert idctr.valid_from == dt.datetime(1970, 1, 1, 0, 0, 1, tzinfo=pytz.utc)
     assert idctr.labels[0] == "malicious-activity"
     assert idctr.pattern == "[file:hashes.MD5 = 'd41d8cd98f00b204e9800998ecf8427e']"
+
+
+def test_invalid_indicator_pattern():
+    with pytest.raises(stix2.exceptions.InvalidValueError) as excinfo:
+        stix2.Indicator(
+            labels=['malicious-activity'],
+            pattern="file:hashes.MD5 = 'd41d8cd98f00b204e9800998ecf8427e'",
+        )
+    assert excinfo.value.cls == stix2.Indicator
+    assert excinfo.value.prop_name == 'pattern'
+    assert 'input is missing square brackets' in excinfo.value.reason
+
+    with pytest.raises(stix2.exceptions.InvalidValueError) as excinfo:
+        stix2.Indicator(
+            labels=['malicious-activity'],
+            pattern='[file:hashes.MD5 = "d41d8cd98f00b204e9800998ecf8427e"]',
+        )
+    assert excinfo.value.cls == stix2.Indicator
+    assert excinfo.value.prop_name == 'pattern'
+    assert 'mismatched input' in excinfo.value.reason