Emails Found in the Viewstate

The 'Emails Found in the Viewstate' vulnerability occurs when sensitive data, such as email addresses, is stored in the viewstate, a hidden field that is used to store data between postbacks in a web application. This vulnerability can be exploited by attackers to gain access to sensitive data, compromise user privacy, and potentially launch further attacks.

To fix this vulnerability, we need to ensure that sensitive data is not stored in the viewstate. Below are the steps that you can follow to fix this vulnerability:

‍

Step 1: Identify where the sensitive data is being stored

The first step is to identify where the sensitive data is being stored. You can use a tool such as a web proxy, such as Burp Suite or ZAP, to intercept and inspect the HTTP requests and responses exchanged between the web application and the server. Look for any instances where email addresses or other sensitive data is being sent in the viewstate.

‍

Step 2: Remove the sensitive data from the viewstate

Once you have identified where the sensitive data is being stored, you need to remove it from the viewstate. There are different ways to do this depending on the programming language and framework being used. Here are a few examples:

ASP.NET Web Forms:

If you are using ASP.NET Web Forms, you can use the EnableViewStateMac and ViewStateEncryptionMode properties to encrypt and sign the viewstate. This will prevent attackers from tampering with the viewstate and accessing sensitive data. To enable viewstate encryption and signing, you can add the following code to the web.config file:

<system.web> <pages enableViewStateMac="true" ViewStateEncryptionMode="Always" /> </system.web>

‍

Alternatively, you can disable viewstate altogether for controls that do not require it. You can do this by setting the EnableViewState property of the control to false:

<asp:TextBox ID="EmailTextBox" runat="server" EnableViewState="false"></asp:TextBox>

‍

If you are using ASP.NET MVC, you can use the TempData property to store data between requests instead of the viewstate. TempData is a session-like storage mechanism that is used to pass data between actions. To use TempData, you need to add the following code to the controller action that receives the sensitive data:

TempData["Email"] = email;

‍

Then, in the action that retrieves the data, you can access it as follows:

string email = (string)TempData["Email"];

Note that TempData data is cleared after it is read, so you should only use it for temporary storage.

‍

If you are using PHP, you can use the $_SESSION variable to store data between requests instead of the viewstate. $_SESSION is a superglobal variable that is used to store data between requests. To store the sensitive data, you can add the following code to the PHP script that receives the data:

session_start(); $_SESSION["email"] = $email;

‍

Then, in the script that retrieves the data, you can access it as follows:

session_start(); $email = $_SESSION["email"];

‍

Step 3: Test the application for the vulnerability

After you have removed the sensitive data from the viewstate, you should test the application again to ensure that the vulnerability has been fixed. You can use the same vulnerability scanner that you used initially to scan the application and check if the vulnerability has been resolved.

‍

Step 4: Monitor the application for future vulnerabilities

It is important to monitor the application for future vulnerabilities and take steps to fix them as soon as they are discovered. You can use a web application firewall (WAF) to detect and prevent attacks against the application. A WAF can analyze the  incoming and outgoing traffic of the web application and block any requests that contain malicious payloads or exploit known vulnerabilities.

In addition to a WAF, it is also recommended to conduct regular security audits and penetration testing of the application to identify and fix vulnerabilities before they can be exploited by attackers.

‍

Conclusion:

The 'Emails Found in the Viewstate' vulnerability is a serious security issue that can compromise user privacy and lead to further attacks. To fix this vulnerability, we need to ensure that sensitive data is not stored in the viewstate. This can be achieved by encrypting and signing the viewstate, using alternative storage mechanisms such as TempData in ASP.NET MVC or $_SESSION in PHP, and regularly monitoring the application for future vulnerabilities.

It is essential to prioritize the security of web applications and take proactive measures to protect against vulnerabilities. By following the steps outlined in this manual, you can fix the 'Emails Found in the Viewstate' vulnerability and reduce the risk of your application being compromised by attackers.

‍