[medium] Avoid condition-variable collisions for dotted field names

sigma/backends/splunk/splunk.py

@@ -64,13 +64,16 @@ def clean_field(field):
 
     @classmethod
     def add_field(cls, field):
-        cls.field_counts[field] = (
-            cls.field_counts.get(field, 0) + 1
+        # Count by the cleaned name: fields like a.x and b.x both map to the
+        # variable prefix "x" and must get different suffixes.
+        cleaned_field = cls.clean_field(field)
+        cls.field_counts[cleaned_field] = (
+            cls.field_counts.get(cleaned_field, 0) + 1
         )  # increment the field count
 
     @classmethod
     def get_field_suffix(cls, field):
-        index_suffix = cls.field_counts.get(field, "")
+        index_suffix = cls.field_counts.get(cls.clean_field(field), "")
         if index_suffix == 1:
             index_suffix = ""
         return index_suffix

tests/test_backend_splunk.py

@@ -415,6 +415,50 @@ def test_splunk_disjunction_with_deferred_regex_no_search_or():
     assert 'NOT fieldBCondition="true"' in query
 
 
+def test_splunk_or_regex_dotted_fields_same_suffix(splunk_backend: SplunkBackend):
+    """Fields a.x and b.x both clean to "x"; they must not share the rex/eval
+    variables, otherwise the second eval overwrites the first."""
+    SplunkDeferredORRegularExpression.reset()
+    result = splunk_backend.convert(
+        SigmaCollection.from_yaml(
+            """
+            title: Test
+            status: test
+            logsource:
+                category: test_category
+                product: test_product
+            detection:
+                sel_a:
+                    a.x|re: 'A'
+                filter_b:
+                    b.x|re: 'B'
+                condition: sel_a or not filter_b
+        """
+        )
+    )
+    assert result == [
+        '\n| rex field=a.x "(?<xMatch>A)"'
+        '\n| eval xCondition=if(isnotnull(xMatch), "true", "false")'
+        '\n| rex field=b.x "(?<xMatch2>B)"'
+        '\n| eval xCondition2=if(isnotnull(xMatch2), "true", "false")'
+        '\n| search xCondition="true" OR NOT xCondition2="true"'
+    ]
+
+
+def test_splunk_or_regex_dotted_fields_condition_names():
+    SplunkDeferredORRegularExpression.reset()
+    SplunkDeferredORRegularExpression.add_field("a.x")
+    assert SplunkDeferredORRegularExpression.get_field_condition("a.x") == "xCondition"
+    SplunkDeferredORRegularExpression.add_field("b.x")
+    assert SplunkDeferredORRegularExpression.get_field_condition("b.x") == "xCondition2"
+    assert SplunkDeferredORRegularExpression.get_field_match("b.x") == "xMatch2"
+    assert SplunkDeferredORRegularExpression.get_all_condition_fields() == {
+        "xCondition",
+        "xCondition2",
+    }
+    SplunkDeferredORRegularExpression.reset()
+
+
 _AND_REGEX_OR_RULE = """
     title: Test
     status: test