Merge pull request #437 from bridgecrewio/feature/check_bucket_policies_public_write

Check bucket policies public write

checks/check_extra771

@@ -0,0 +1,39 @@
+#!/usr/bin/env bash
+
+# Prowler - the handy cloud security tool (copyright 2018) by Toni de la Fuente
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may not
+# use this file except in compliance with the License. You may obtain a copy
+# of the License at http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software distributed
+# under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+# CONDITIONS OF ANY KIND, either express or implied. See the License for the
+# specific language governing permissions and limitations under the License.
+CHECK_ID_extra771="7.71"
+CHECK_TITLE_extra771="[extra771] Check if S3 buckets have policies which allow WRITE access (Not Scored) (Not part of CIS benchmark)"
+CHECK_SCORED_extra771="NOT_SCORED"
+CHECK_TYPE_extra771="EXTRA"
+CHECK_ALTERNATE_check771="extra771"
+
+extra771(){
+  LIST_OF_BUCKETS=$($AWSCLI s3api list-buckets $PROFILE_OPT --query Buckets[*].Name --output text|xargs -n1)
+  if [[ $LIST_OF_BUCKETS ]]; then
+    for bucket in $LIST_OF_BUCKETS;do
+      BUCKET_POLICY_STATEMENTS=$($AWSCLI s3api $PROFILE_OPT get-bucket-policy --bucket $bucket --output json --query Policy 2>&1)
+      if [[ $BUCKET_POLICY_STATEMENTS == *GetBucketPolicy* ]]; then
+        textInfo "Bucket policy does not exist for bucket $bucket"
+      else
+        BUCKET_POLICY_BAD_STATEMENTS=$(echo $BUCKET_POLICY_STATEMENTS | jq --arg arn "arn:aws:s3:::$bucket" 'fromjson | .Statement[]|select(.Effect=="Allow" and (((.Principal|type == "object") and .Principal.AWS == "*") or ((.Principal|type == "string") and .Principal == "*")) and (.Action|startswith("s3:Put") or startswith("s3:*")))')
+        if [[ $BUCKET_POLICY_BAD_STATEMENTS != "" ]]; then
+          textFail "Bucket $bucket allows public write: $BUCKET_POLICY_BAD_STATEMENTS"
+        else
+          textPass "Bucket $bucket has S3 bucket policy which does not allow public write access"
+        fi
+      fi
+    done
+
+  else
+    textInfo "No S3 Buckets found"
+  fi
+}