This Repository contains CORS misconfiguration related vulnerable codes. One can configure the vulnerable code on local machine to perform practical exploitation of CORS related misconfiguration issues.

I would like to say Thank You to @albinowax (For his work in CORS exploitation), AKReddy and Vivek Sir (For being great personalities who always supported me) and Andrew Sir - @vanderaj (for his encouraging words)

Following are the pre-requities to configure the vulnerable code on local/remote machine

1. Apache web server
2. PHP 5/7
3. MySQL Database

Steps to Configure:

1. Download and extract the codes in "htdocs" or webroot directory of the web server.

2. Open PHPMyAdmin and create new database with name "ica_lab".

3. If you want to use MySQL "root" user account, skip below mentioned step and jump to step no. 5.

4. create a new user having name "billu" by executing below mentioned SQL command: (skip step no. 5)

     grant all on ica_lab.* to billu@localhost IDENTIFIED BY 'b0x_billu';
   

5. Open "c0nnection.php" in text editor and make below mentioned changes in the PHP:

      change 
      $conn = mysqli_connect("127.0.0.1","billu","b0x_billu","ica_lab");
      to
      $conn = mysqli_connect("127.0.0.1","root","","ica_lab");
   

6. In PHPMyAdmin, select "database" and then click database name "ica_lab".

7. Click "Import" button and browse the locate the SQL dump file "ica_lab.sql" on your local machine. This file is present in directory "database" of the repository.

8. After browsing the SQL database file, click "Go" button. Now. database is ready.

9. Access the "CORS Vulnerable Lab" application.

10. Login credentials are already specified in input fileds, just click "Let Me In" button and you are ready to play with the lab.

There are 3 misconfiguration which are simulated in this Lab.

Application Trust Arbitrary Origin

Application accept CORS request from any Origin. The code put the "Origin" value in HTTP response header "Access-Control-Allow-Origin". Now, this configuration will allow any script from any "Origin" to make CORS request to application. Web browser will perform standard CORS request checks and Script from malicious domain will be able to steal the data.

Application has bad "regex" Implementation to check Trusted Origin

Application has CORS policy implemented and perform "Regex" check for whitelisted Domain/Sub-domains. In this scenario, application has weak regex implementation in code which just check for presence of domain name "b0x.com" anywhere in HTTP request "Origin" header. If HTTP header "Origin" has value "inb0x.com" or b0x.comlab.com, regex will mark it pass. This misconfiguration will lead to sharing of data over cross origin.

Application Trust "null" Origin

In this scenario, application HTTP response header "Access-Control-Allow-Origin" is always set to "null". When user specify any value other than null, application does not process it and keep reflecting "null" in HTTP response. There are few tricks which allow an attacker to perform exploitation and can ex-filtrate data of victim using CORS request.

Examples:

Application Trust Arbitrary Origin

Application accept any value specified in "Origin" header.

Exploitation Demo

Application has bad "regex" Implementation to check Trusted Origin

Application is trusting whitelisted Origin.

Application is not allowing any arbitrary Origin.

Application weak regex allowing an Origin which has whitelisted domain string in starting of the domain name.

Application weak regex allowing an Origin which has whitelisted domain string in the end of the domain name.

Application Trust "null" Origin

Application accept "null" value specified in "Origin" header.

Application is not accepting any value other then "null" "Origin".

Exploitation Demo

Ex-filtrating data to attacker controlled server

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