diff --git a/Dockerfile b/Dockerfile
index 3cb28c0bcc..5565a01717 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,10 +1,13 @@
-FROM python:3.6
+FROM python:3.6-slim
 
-RUN apt-get -y update && apt-get -y install ffmpeg
+# Security: Be specific on version, so use ffmpeg=<version>
+RUN apt-get update && apt-get -y upgrade && apt-get install -y ffmpeg
 # RUN apt-get -y update && apt-get -y install git wget python-dev python3-dev libopenmpi-dev python-pip zlib1g-dev cmake python-opencv
 
 ENV CODE_DIR /root/code
 
+# Security: Preserve the ownership of the files and directories, so that the files are owned by the right user and group.
+# So use COPY --chown=<user:group> . $CODE_DIR/baselines
 COPY . $CODE_DIR/baselines
 WORKDIR $CODE_DIR/baselines
 
@@ -13,6 +16,6 @@ RUN rm -rf __pycache__ && \
     find . -name "*.pyc" -delete && \
     pip install 'tensorflow < 2' && \
     pip install -e .[test]
-
-
-CMD /bin/bash
+    
+RUN apt-get clean
+CMD ["/bin/bash"]