Guessable API Endpoint Leads to Bypass Email Verification in UK Government Website Registration Page

Core Concepts

Improper authentication implementation in a UK government website's registration process allowed an attacker to bypass email verification and gain unauthorized access to an admin account.

Abstract

The author discovered a vulnerability in the registration process of a UK government website that allowed bypassing email verification. The key insights are:

The website had a registration page where users could create accounts and manage their data, including signing up for newsletters, courses, and competitions.
During the registration process, the website sent an email confirmation with a token ID and username.
The author observed that the token ID was easily guessable, as it only differed by a single digit between different user accounts.
By crafting a guessable URL with the predicted token ID, the author was able to bypass the email verification process and gain access to an admin account ([e-mail]) without having the actual email address.
This vulnerability allowed the author to effectively pre-take over the admin account, demonstrating a significant security flaw in the website's authentication implementation.
The author reported the issue and is awaiting the team's confirmation and further updates.

Stats

www.redacted.com/Webaccount?SignupID=NHKS-001026912_075&LDAP_account=victim_user
www.redacted.com/Webaccount?SignupID=NHKS-001026913_075&LDAP_account=attacker_account
www.redacted.com/Webaccount?SignupID=NHKS-001026914_075&LDAP_account=admingovuk

Quotes

"Even though it's just a pre-account takeover, the guessable API token affected the whole registration functionality. As a result, I was logged in as [e-mail]."

Key Insights Distilled From

Email Verification Bypass Easy-P4

by at medium.com 08-02-2024

https://medium.com/@Ajakcybersecurity/email-verification-bypass-easy-p4-70039d0b8fd9

Deeper Inquiries

What other types of vulnerabilities could exist in the website's authentication and authorization mechanisms beyond the email verification bypass?

In addition to the email verification bypass vulnerability, other vulnerabilities that could exist in the website's authentication and authorization mechanisms include:

Weak Password Policies: If the website allows users to set weak passwords or does not enforce password complexity requirements, it could lead to brute force attacks or password guessing.
Session Management Issues: Improper session management, such as not expiring sessions after a period of inactivity or not properly handling session tokens, could result in unauthorized access to user accounts.
Insecure Direct Object References: If the website exposes internal implementation details in URLs or parameters, attackers could manipulate these references to access unauthorized resources.
Cross-Site Scripting (XSS): If the website does not properly sanitize user input, it could be vulnerable to XSS attacks, where malicious scripts are injected into the website and executed in users' browsers.
SQL Injection: If the website's authentication process is vulnerable to SQL injection attacks, attackers could manipulate SQL queries to gain unauthorized access to the database.

How could the website's developers have implemented a more secure and robust registration process to prevent such guessable token issues?

To prevent guessable token issues and enhance the security of the registration process, the website's developers could have implemented the following measures:

Use Strong Random Tokens: Generate unique, strong, and random tokens for email verification instead of predictable or sequential values that can be easily guessed.
Token Expiration: Set an expiration time for the verification tokens to limit the window of opportunity for attackers to exploit guessable tokens.
Token Revocation: Implement a mechanism to revoke or invalidate tokens once they have been used to prevent reuse or unauthorized access.
Rate Limiting: Implement rate limiting on the number of verification attempts to prevent brute force attacks on the token generation process.
Multi-Factor Authentication: Require users to verify their identity through multiple factors, such as email verification combined with SMS verification, to add an extra layer of security to the registration process.

What are the potential real-world implications and risks of such a vulnerability in a government website, and how could it be exploited by malicious actors?

The vulnerability of guessable tokens in a government website's registration process poses significant risks and implications:

Unauthorized Access: Malicious actors could exploit the vulnerability to gain unauthorized access to sensitive government data, user accounts, or administrative functionalities.
Data Breach: If an attacker successfully takes over an admin account, they could potentially access and manipulate confidential government information, leading to a data breach.
Manipulation of Services: Attackers could manipulate government services, alter information, or disrupt operations by gaining unauthorized access through the compromised accounts.
Loss of Trust: A security breach in a government website could erode public trust in the government's ability to protect sensitive information and maintain secure online services.
Legal Consequences: Depending on the severity of the breach and the data compromised, the government website could face legal repercussions, fines, or damage to its reputation.

By exploiting this vulnerability, malicious actors could compromise the integrity and security of the government website, potentially leading to severe consequences for both the government and its users.