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Lack of data validation - Session Cookie

Need​

Implementation of secure data validation for Session Cookies

Context​

  • Usage of Java 8 for developing applications with enhanced features and performance improvements
  • Usage of javax.servlet-api for developing Java web applications using servlets

Description​

Non compliant code​

import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class SessionController {

    public void setSessionCookie(HttpServletRequest request, HttpServletResponse response) {
        String sessionId = request.getParameter("sessionId");
        Cookie sessionCookie = new Cookie("SessionId", sessionId);
        response.addCookie(sessionCookie);
    }
}

The above code is a simple example of a servlet that handles session cookies. The setSessionCookie method retrieves a session ID from a request parameter and directly uses this value to create a new cookie, which is then added to the HTTP response.

The vulnerability lies in the lack of validation of the sessionId parameter. The method blindly trusts the session ID value sent from the client, without checking its legitimacy or integrity. This could allow an attacker to manipulate the session ID value, potentially leading to session fixation or session hijacking attacks.

For instance, an attacker could trick a victim into using a session ID controlled by the attacker, and then use that session ID to impersonate the victim. Alternatively, an attacker could manipulate their own session ID to gain unauthorized access to the system.

This vulnerability could be exploited if an attacker has control over the session ID value sent in the request, which could happen if the application uses insecure communication channels, or if the attacker can trick the user into submitting a crafted request.

Steps​

  • Implement input validation to ensure that the sessionId parameter is a valid and secure value.
  • Use a secure method to generate the session cookie value instead of using the sessionId parameter directly.
  • Consider using a secure session management framework or library to handle session management instead of manually setting the session cookie.

Compliant code​

import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.UUID;

public class SessionController {

    public void setSessionCookie(HttpServletRequest request, HttpServletResponse response) {
        String sessionId = request.getParameter("sessionId");
        if (isValid(sessionId)) {
            Cookie sessionCookie = new Cookie("SessionId", generateSecureSessionId());
            response.addCookie(sessionCookie);
        }
    }

    private boolean isValid(String sessionId) {
        // Implement your validation logic here
        // For example, check if the sessionId is not null and matches a certain pattern
        return sessionId != null && sessionId.matches("[a-zA-Z0-9]{16}");
    }

    private String generateSecureSessionId() {
        // Generate a secure session ID using UUID
        return UUID.randomUUID().toString();
    }
}

The updated code includes a validation method isValid() to check if the sessionId parameter is a valid and secure value. This method can be customized to include any specific validation logic as per the application's requirements.

The setSessionCookie() method now checks if the sessionId is valid before setting the session cookie. If the sessionId is not valid, the method will not set the session cookie, thus preventing the use of an insecure session cookie.

Additionally, the generateSecureSessionId() method is used to generate a secure session ID using UUID. This method replaces the direct use of the sessionId parameter, further enhancing the security of the session cookie.

It's also recommended to use a secure session management framework or library to handle session management, which can provide additional security features and reduce the risk of errors in manual session management.

References​

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