diff --git a/api/src/search/backend/load_opportunities_to_index.py b/api/src/search/backend/load_opportunities_to_index.py
index a1e7d0c9c..178cc6f32 100644
--- a/api/src/search/backend/load_opportunities_to_index.py
+++ b/api/src/search/backend/load_opportunities_to_index.py
@@ -3,7 +3,6 @@
 from enum import StrEnum
 from typing import Iterator, Sequence
 
-import smart_open
 from opensearchpy.exceptions import ConnectionTimeout, TransportError
 from pydantic import Field
 from pydantic_settings import SettingsConfigDict
@@ -22,11 +21,16 @@
     OpportunitySearchIndexQueue,
 )
 from src.task.task import Task
+from src.util import file_util
 from src.util.datetime_util import get_now_us_eastern_datetime
 from src.util.env_config import PydanticBaseEnvConfig
 
 logger = logging.getLogger(__name__)
 
+ALLOWED_ATTACHMENT_SUFFIXES = set(
+    ["txt", "pdf", "docx", "doc", "xlsx", "xlsm", "html", "htm", "pptx", "ppt", "rtf"]
+)
+
 
 class LoadOpportunitiesToIndexConfig(PydanticBaseEnvConfig):
     model_config = SettingsConfigDict(env_prefix="LOAD_OPP_SEARCH_")
@@ -275,10 +279,9 @@ def fetch_existing_opportunity_ids_in_index(self) -> set[int]:
 
         return opportunity_ids
 
-    def filter_attachments(
-        self, attachments: list[OpportunityAttachment]
-    ) -> list[OpportunityAttachment]:
-        return [attachment for attachment in attachments]
+    def filter_attachment(self, attachment: OpportunityAttachment) -> bool:
+        file_suffix = attachment.file_name.lower().split(".")[-1]
+        return file_suffix in ALLOWED_ATTACHMENT_SUFFIXES
 
     def get_attachment_json_for_opportunity(
         self, opp_attachments: list[OpportunityAttachment]
@@ -286,17 +289,18 @@ def get_attachment_json_for_opportunity(
 
         attachments = []
         for att in opp_attachments:
-            with smart_open.open(
-                att.file_location,
-                "rb",
-            ) as file:
-                file_content = file.read()
-                attachments.append(
-                    {
-                        "filename": att.file_name,
-                        "data": base64.b64encode(file_content).decode("utf-8"),
-                    }
-                )
+            if self.filter_attachment(att):
+                with file_util.open_stream(
+                    att.file_location,
+                    "rb",
+                ) as file:
+                    file_content = file.read()
+                    attachments.append(
+                        {
+                            "filename": att.file_name,
+                            "data": base64.b64encode(file_content).decode("utf-8"),
+                        }
+                    )
 
         return attachments
 
diff --git a/api/tests/src/search/backend/test_load_opportunities_to_index.py b/api/tests/src/search/backend/test_load_opportunities_to_index.py
index 64a5190f1..36296baaa 100644
--- a/api/tests/src/search/backend/test_load_opportunities_to_index.py
+++ b/api/tests/src/search/backend/test_load_opportunities_to_index.py
@@ -149,18 +149,27 @@ def test_opportunity_attachment_pipeline(
         opportunity_index_alias,
         search_client,
     ):
-        filename = "test_file_1.txt"
-        file_path = f"s3://{mock_s3_bucket}/{filename}"
+        filename_1 = "test_file_1.txt"
+        file_path_1 = f"s3://{mock_s3_bucket}/{filename_1}"
         content = "I am a file"
-        with file_util.open_stream(file_path, "w") as outfile:
+
+        with file_util.open_stream(file_path_1, "w") as outfile:
             outfile.write(content)
 
+        filename_2 = "test_file_2.css"
+        file_path_2 = f"s3://{mock_s3_bucket}/{filename_2}"
+
         opportunity = OpportunityFactory.create(opportunity_attachments=[])
         OpportunityAttachmentFactory.create(
-            mime_type="text/plain",
             opportunity=opportunity,
-            file_location=file_path,
-            file_name=filename,
+            file_location=file_path_1,
+            file_name=filename_1,
+        )
+
+        OpportunityAttachmentFactory.create(
+            opportunity=opportunity,
+            file_location=file_path_2,
+            file_name=filename_2,
         )
 
         load_opportunities_to_index.index_name = (
@@ -172,11 +181,14 @@ def test_opportunity_attachment_pipeline(
         resp = search_client.search(opportunity_index_alias, {"size": 100})
 
         record = [d for d in resp.records if d.get("opportunity_id") == opportunity.opportunity_id]
-        attachment = record[0]["attachments"][0]
+        attachments = record[0]["attachments"]
+
+        # assert only one (allowed) opportunity attachment was uploaded
+        assert len(attachments) == 1
         # assert correct attachment was uploaded
-        assert attachment["filename"] == filename
+        assert attachments[0]["filename"] == filename_1
         # assert data was b64encoded
-        assert attachment["attachment"]["content"] == content  # decoded b64encoded attachment
+        assert attachments[0]["attachment"]["content"] == content  # decoded b64encoded attachment
 
 
 class TestLoadOpportunitiesToIndexPartialRefresh(BaseTestClass):