Account Takeover Vulnerability Due to Missing Email Verification

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Bug Bounty Writeup: Account Takeover Vulnerability

Report ID: [REDACTED ID] Vulnerability: Account Takeover due to Missing Email Verification Severity: Medium (CVSS: 6.6) Status: Closed (Duplicate) Program: [Target Program]

Summary

An account takeover vulnerability was identified in the [Target Program]’s website due to the absence of email verification during user registration. This flaw allowed attackers to register accounts using fake or other users’ email addresses, leading to potential unauthorized access and malicious activities.

Description

The vulnerability stemmed from a critical oversight in the user registration process: the lack of a robust email validation mechanism. This allowed users to complete registration with unverified email addresses, including those that were falsified or belonged to legitimate users.

This absence of rigorous email validation significantly increased the risk of unauthorized account access. Malicious actors could exploit this loophole to register using legitimate email addresses of other users, potentially gaining unauthorized access to their accounts. Such unauthorized access could lead to various harmful outcomes, including:

• Access to sensitive information
• Fraudulent activities
• Privacy breaches
• Financial losses for victims
• Compromised personal information
• Reputational damage for both individuals and the platform.

Promptly addressing this issue is crucial to safeguard user accounts and maintain the integrity of the platform. Implementing robust validation mechanisms is paramount to prevent malicious exploitation and mitigate the risk of account theft.

Steps To Reproduce

1. Navigate to the user registration page.
2. Enter a victim’s email address (or a fake email address) during registration.
3. Complete the registration process without any email verification being enforced.
4. Observe that an account is successfully created without the need to confirm the email address.

(Note: These steps are generalized to protect specific program details.)

Impact

The primary impact of this vulnerability was the potential for full account takeover. An attacker could register an account associated with a victim’s email address without the victim’s consent or knowledge. This could lead to:

• Unauthorized access to the victim’s personal data.
• Ability to perform actions on behalf of the victim.
• Compromise of the victim’s privacy and security.

Remediation (Suggested)

To mitigate this vulnerability, the following actions were suggested:

• Implement a mandatory email verification process during user registration. This typically involves sending a unique verification link or code to the provided email address, which the user must click or enter to activate their account.
• Ensure that all new account registrations require a confirmed email address before granting full access to the platform’s features.

Conclusion

This report highlights the importance of comprehensive email verification in preventing account takeover vulnerabilities. Even seemingly minor omissions in validation can lead to significant security risks. The program acknowledged the report, and while it was marked as a duplicate, the issue underscores a common vulnerability that all web applications should address.