diff --git a/x-pack/solutions/security/plugins/security_solution/server/lib/detection_engine/rule_schema/model/rule_schemas.ts b/x-pack/solutions/security/plugins/security_solution/server/lib/detection_engine/rule_schema/model/rule_schemas.ts
index c1192e9a75fd1..ae9faa8bb006a 100644
--- a/x-pack/solutions/security/plugins/security_solution/server/lib/detection_engine/rule_schema/model/rule_schemas.ts
+++ b/x-pack/solutions/security/plugins/security_solution/server/lib/detection_engine/rule_schema/model/rule_schemas.ts
@@ -104,6 +104,14 @@ export const RuleSourceCamelCased = z.discriminatedUnion('type', [
   z.object({
     type: z.literal('external'),
     isCustomized: IsExternalRuleCustomized,
+    customizedFields: z
+      .array(
+        z.object({
+          fieldName: z.string(),
+        })
+      )
+      .optional(),
+    hasBaseVersion: z.boolean().optional(),
   }),
   z.object({
     type: z.literal('internal'),