[StepSecurity] Apply security best practices

Signed-off-by: StepSecurity Bot <bot@stepsecurity.io>

.github/workflows/adhoctest.yml

@@ -25,6 +25,9 @@ on:
     paths:
       - '**/workflows/adhoctest.yml'
 
+permissions:
+  contents: read
+
 jobs:
   build:
 

.github/workflows/dependency-review.yml

@@ -0,0 +1,22 @@
+# Dependency Review Action
+#
+# This Action will scan dependency manifest files that change as part of a Pull Request,
+# surfacing known-vulnerable versions of the packages declared or updated in the PR.
+# Once installed, if the workflow run is marked as required,
+# PRs introducing known-vulnerable packages will be blocked from merging.
+#
+# Source repository: https://github.com/actions/dependency-review-action
+name: 'Dependency Review'
+on: [pull_request]
+
+permissions:
+  contents: read
+
+jobs:
+  dependency-review:
+    runs-on: ubuntu-latest
+    steps:
+      - name: 'Checkout Repository'
+        uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # v3.5.3
+      - name: 'Dependency Review'
+        uses: actions/dependency-review-action@0efb1d1d84fc9633afcdaad14c485cbbc90ef46c # v2.5.1

src/docker/Dockerfile

@@ -17,7 +17,7 @@
 # for Linux 64-bit and 32-bit, and Windows 64-bit and 32-bit.
 # See the README for further details.
 
-FROM ubuntu:18.04
+FROM ubuntu:18.04@sha256:152dc042452c496007f07ca9127571cb9c29697f42acbfad72324b2bb2e43c98
 
 ENV JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64
 ENV MAVEN_HOME=/opt/maven