CVE-2024-32651

changedetection.io is an open source web page change detection, website watcher, restock monitor and notification service. There is a Server Side Template Injection (SSTI) in Jinja2 that allows Remote Command Execution on the server host. Attackers can run any system command without any restriction and they could use a reverse shell. The impact is critical as the attacker can completely takeover the server machine. This can be reduced if changedetection is behind a login page, but this isn't required by the application (not by default and not enforced).

changedetection.io is an open source web page change detection, website watcher, restock monitor and notification service. There is a Server Side Template Injection (SSTI) in Jinja2 that allows Remote Command Execution on the server host. Attackers can run any system command without any restriction and they could use a reverse shell. The impact is critical as the attacker can completely takeover the server machine. This can be reduced if changedetection is behind a login page, but this isn't required by the application (not by default and not enforced).

### Summary A Server Side Template Injection in changedetection.io caused by usage of unsafe functions of Jinja2 allows Remote Command Execution on the server host. ### Details changedetection.io version: 0.45.20 ``` docker images REPOSITORY TAG IMAGE ID CREATED SIZE dgtlmoon/changedetection.io latest 53529c2e69f1 44 hours ago 423MB ``` The vulnerability is caused by the usage of vulnerable functions of Jinja2 template engine. ```python from jinja2 import Environment, BaseLoader ... # Get the notification body from datastore jinja2_env = Environment(loader=BaseLoader) n_body = jinja2_env.from_string(n_object.get('notification_body', '')).render(**notification_parameters) n_title = jinja2_env.from_string(n_object.get('notification_title', '')).render(**notification_parameters) ``` ### PoC 1. Create/Edit a URL watch item 2. Under *Notifications* tab insert this payload: ```python {{ self.__init__.__globals__.__builtins__.__import__('os').popen('id').read() }} ```  3. See Telegram (or other supported messaging app) notification  ### Impact In the PoC I've used `id` as payload and Telegram to read the result. Attackers can run any system command without any restriction and they don't need to read the result in the notification app (e.g. they could use a reverse shell). The impact is critical as the attacker can completely takeover the server host. This can be reduced if changedetection access is protected by login page with a password, but this isn't required by the application (not by default and not enforced). ### References - https://www.hacktivesecurity.com/blog/2024/05/08/cve-2024-32651-server-side-template-injection-changedetection-io/ - https://book.hacktricks.xyz/pentesting-web/ssti-server-side-template-injection/jinja2-ssti - https://www.onsecurity.io/blog/server-side-template-injection-with-jinja2/ - https://docs.cobalt.io/bestpractices/prevent-ssti/ ### Credits Edoardo Ottavianelli

### Summary A Server Side Template Injection in changedetection.io caused by usage of unsafe functions of Jinja2 allows Remote Command Execution on the server host. ### Details changedetection.io version: 0.45.20 ``` docker images REPOSITORY TAG IMAGE ID CREATED SIZE dgtlmoon/changedetection.io latest 53529c2e69f1 44 hours ago 423MB ``` The vulnerability is caused by the usage of vulnerable functions of Jinja2 template engine. ```python from jinja2 import Environment, BaseLoader ... # Get the notification body from datastore jinja2_env = Environment(loader=BaseLoader) n_body = jinja2_env.from_string(n_object.get('notification_body', '')).render(**notification_parameters) n_title = jinja2_env.from_string(n_object.get('notification_title', '')).render(**notification_parameters) ``` ### PoC 1. Create/Edit a URL watch item 2. Under *Notifications* tab insert this payload: ```python {{ self.__init__.__globals__.__builtins__.__import__('os').popen('id').read() }} ```  3. See Telegram (or other supported messaging app) notification  ### Impact In the PoC I've used `id` as payload and Telegram to read the result. Attackers can run any system command without any restriction and they don't need to read the result in the notification app (e.g. they could use a reverse shell). The impact is critical as the attacker can completely takeover the server host. This can be reduced if changedetection access is protected by login page with a password, but this isn't required by the application (not by default and not enforced). ### References - https://www.hacktivesecurity.com/blog/2024/05/08/cve-2024-32651-server-side-template-injection-changedetection-io/ - https://book.hacktricks.xyz/pentesting-web/ssti-server-side-template-injection/jinja2-ssti - https://www.onsecurity.io/blog/server-side-template-injection-with-jinja2/ - https://docs.cobalt.io/bestpractices/prevent-ssti/ ### Credits Edoardo Ottavianelli

changetection.io es un servicio de detección de cambios de páginas web, seguimiento de sitios web, monitor de reabastecimiento y notificación de código abierto. Hay una inyección de plantilla del lado del servidor (SSTI) en Jinja2 que permite la ejecución remota de comandos en el host del servidor. Los atacantes pueden ejecutar cualquier comando del sistema sin ninguna restricción y podrían usar un shell inverso. El impacto es crítico ya que el atacante puede apoderarse completamente de la máquina servidor. Esto se puede reducir si la detección de cambios está detrás de una página de inicio de sesión, pero la aplicación no lo requiere (no es de forma predeterminada ni obligatorio).