From d50c3afebd00d22f590e905da48d162db1a88bd2 Mon Sep 17 00:00:00 2001
From: gabrielsoltz <thegaby@gmail.com>
Date: Thu, 13 Jun 2019 12:04:52 +0200
Subject: [PATCH] add check for explicit deny

---
 checks/check_extra73 | 53 +++++++++++++++++++++++++-------------------
 1 file changed, 30 insertions(+), 23 deletions(-)

diff --git a/checks/check_extra73 b/checks/check_extra73
index 216d198f..915e26d4 100644
--- a/checks/check_extra73
+++ b/checks/check_extra73
@@ -53,31 +53,38 @@ extra73(){
     if [[ "EU" == $BUCKET_LOCATION ]]; then
       BUCKET_LOCATION="eu-west-1"
     fi
-    # check if AllUsers is in the ACL as Grantee
-    CHECK_BUCKET_ALLUSERS_ACL=$($AWSCLI s3api get-bucket-acl $PROFILE_OPT --region $BUCKET_LOCATION --bucket $bucket --query "Grants[?Grantee.URI == 'http://acs.amazonaws.com/groups/global/AllUsers']" --output text |grep -v GRANTEE)
-    CHECK_BUCKET_ALLUSERS_ACL_SINGLE_LINE=$(echo -ne $CHECK_BUCKET_ALLUSERS_ACL)
-    # check if AuthenticatedUsers is in the ACL as Grantee, they will have access with sigened URL only
-    CHECK_BUCKET_AUTHUSERS_ACL=$($AWSCLI s3api get-bucket-acl $PROFILE_OPT --region $BUCKET_LOCATION --bucket $bucket --query "Grants[?Grantee.URI == 'http://acs.amazonaws.com/groups/global/AuthenticatedUsers']" --output text |grep -v GRANTEE)
-    CHECK_BUCKET_AUTHUSERS_ACL_SINGLE_LINE=$(echo -ne $CHECK_BUCKET_AUTHUSERS_ACL)
-    # to prevent error NoSuchBucketPolicy first clean the output controlling stderr
-    TEMP_POLICY_FILE=$(mktemp -t prowler-${ACCOUNT_NUM}-${bucket}.policy.XXXXXXXXXX)
-    $AWSCLI s3api get-bucket-policy $PROFILE_OPT --region $BUCKET_LOCATION --bucket $bucket --output text --query Policy > $TEMP_POLICY_FILE 2> /dev/null
-    # check if the S3 policy has Principal as *
-    CHECK_BUCKET_ALLUSERS_POLICY=$(cat $TEMP_POLICY_FILE | sed -e 's/[{}]/''/g' | awk -v k="text" '{n=split($0,a,","); for (i=1; i<=n; i++) print a[i]}'|awk '/Principal/ && !skip { print } { skip = /Deny/} '|grep ^\"Principal|grep \*)
-    if [[ $CHECK_BUCKET_ALLUSERS_ACL || $CHECK_BUCKET_AUTHUSERS_ACL || $CHECK_BUCKET_ALLUSERS_POLICY ]];then
-      if [[ $CHECK_BUCKET_ALLUSERS_ACL ]];then
-        textFail "$BUCKET_LOCATION: $bucket bucket is open to the Internet (Everyone) with permissions: $CHECK_BUCKET_ALLUSERS_ACL_SINGLE_LINE" "$regx"
-      fi
-      if [[ $CHECK_BUCKET_AUTHUSERS_ACL ]];then
-        textFail "$BUCKET_LOCATION: $bucket bucket is open to Authenticated users (Any AWS user) with permissions: $CHECK_BUCKET_AUTHUSERS_ACL_SINGLE_LINE" "$regx"
-      fi
-      if [[ $CHECK_BUCKET_ALLUSERS_POLICY ]];then
-        textFail "$BUCKET_LOCATION: $bucket bucket policy \"may\" allow Anonymous users to perform actions (Principal: \"*\")" "$regx"
-      fi
+    # Check Explicit Deny and Avoid Error
+    CHEK_FOR_EXPLICIT_DENY=$($AWSCLI s3api get-bucket-acl $PROFILE_OPT --region $BUCKET_LOCATION --bucket $bucket 2> /dev/null)
+    CHEK_FOR_EXPLICIT_DENY="$?"
+    if [[ $CHEK_FOR_EXPLICIT_DENY -eq 255 ]]; then
+      textPass "$BUCKET_LOCATION: bucket have an explicit Deny. Not possible to get ACL." "$regx"
     else
-      textPass "$BUCKET_LOCATION: $bucket bucket is not open" "$regx"
+      # check if AllUsers is in the ACL as Grantee
+      CHECK_BUCKET_ALLUSERS_ACL=$($AWSCLI s3api get-bucket-acl $PROFILE_OPT --region $BUCKET_LOCATION --bucket $bucket --query "Grants[?Grantee.URI == 'http://acs.amazonaws.com/groups/global/AllUsers']" --output text |grep -v GRANTEE)
+      CHECK_BUCKET_ALLUSERS_ACL_SINGLE_LINE=$(echo -ne $CHECK_BUCKET_ALLUSERS_ACL)
+      # check if AuthenticatedUsers is in the ACL as Grantee, they will have access with sigened URL only
+      CHECK_BUCKET_AUTHUSERS_ACL=$($AWSCLI s3api get-bucket-acl $PROFILE_OPT --region $BUCKET_LOCATION --bucket $bucket --query "Grants[?Grantee.URI == 'http://acs.amazonaws.com/groups/global/AuthenticatedUsers']" --output text |grep -v GRANTEE)
+      CHECK_BUCKET_AUTHUSERS_ACL_SINGLE_LINE=$(echo -ne $CHECK_BUCKET_AUTHUSERS_ACL)
+      # to prevent error NoSuchBucketPolicy first clean the output controlling stderr
+      TEMP_POLICY_FILE=$(mktemp -t prowler-${ACCOUNT_NUM}-${bucket}.policy.XXXXXXXXXX)
+      $AWSCLI s3api get-bucket-policy $PROFILE_OPT --region $BUCKET_LOCATION --bucket $bucket --output text --query Policy > $TEMP_POLICY_FILE 2> /dev/null
+      # check if the S3 policy has Principal as *
+      CHECK_BUCKET_ALLUSERS_POLICY=$(cat $TEMP_POLICY_FILE | sed -e 's/[{}]/''/g' | awk -v k="text" '{n=split($0,a,","); for (i=1; i<=n; i++) print a[i]}'|awk '/Principal/ && !skip { print } { skip = /Deny/} '|grep ^\"Principal|grep \*)
+      if [[ $CHECK_BUCKET_ALLUSERS_ACL || $CHECK_BUCKET_AUTHUSERS_ACL || $CHECK_BUCKET_ALLUSERS_POLICY ]];then
+        if [[ $CHECK_BUCKET_ALLUSERS_ACL ]];then
+          textFail "$BUCKET_LOCATION: $bucket bucket is open to the Internet (Everyone) with permissions: $CHECK_BUCKET_ALLUSERS_ACL_SINGLE_LINE" "$regx"
+        fi
+        if [[ $CHECK_BUCKET_AUTHUSERS_ACL ]];then
+          textFail "$BUCKET_LOCATION: $bucket bucket is open to Authenticated users (Any AWS user) with permissions: $CHECK_BUCKET_AUTHUSERS_ACL_SINGLE_LINE" "$regx"
+        fi
+        if [[ $CHECK_BUCKET_ALLUSERS_POLICY ]];then
+          textFail "$BUCKET_LOCATION: $bucket bucket policy \"may\" allow Anonymous users to perform actions (Principal: \"*\")" "$regx"
+        fi
+      else
+        textPass "$BUCKET_LOCATION: $bucket bucket is not open" "$regx"
+      fi
+      rm -fr $TEMP_POLICY_FILE
     fi
-    rm -fr $TEMP_POLICY_FILE
   done
 }