diff --git a/monkey/common/agent_configuration/agent_sub_configuration_schemas.py b/monkey/common/agent_configuration/agent_sub_configuration_schemas.py
index aaece7067..e3f2fe16a 100644
--- a/monkey/common/agent_configuration/agent_sub_configuration_schemas.py
+++ b/monkey/common/agent_configuration/agent_sub_configuration_schemas.py
@@ -1,6 +1,6 @@
 import re
 
-from marshmallow import Schema, fields, post_load, validate
+from marshmallow import Schema, ValidationError, fields, post_load, validate, validates
 
 from .agent_sub_configurations import (
     CustomPBAConfiguration,
@@ -29,6 +29,35 @@ class CustomPBAConfigurationSchema(Schema):
         validate=validate.Regexp(regex=valid_windows_custom_pba_filename_regex)
     )
 
+    @validates("windows_filename")
+    def validate_windows_filename_not_reserved(self, windows_filename):
+        # filename shouldn't start with any of these and be followed by a period
+        if windows_filename.split(".")[0].upper() in [
+            "CON",
+            "PRN",
+            "AUX",
+            "NUL",
+            "COM1",
+            "COM2",
+            "COM3",
+            "COM4",
+            "COM5",
+            "COM6",
+            "COM7",
+            "COM8",
+            "COM9",
+            "LPT1",
+            "LPT2",
+            "LPT3",
+            "LPT4",
+            "LPT5",
+            "LPT6",
+            "LPT7",
+            "LPT8",
+            "LPT9",
+        ]:
+            raise ValidationError("Invalid Windows filename: reserved name used")
+
     @post_load
     def _make_custom_pba_configuration(self, data, **kwargs):
         return CustomPBAConfiguration(**data)