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Task Description
Vulnerability Summary
Title: Privilege Escalation via Unvalidated Invitation Deletion Leading to Unrestricted Account Creation
Severity: High (Potential Impact: Unauthorized Account Proliferation, Bypass of Email Verification)
Vulnerability Type: Logic Flaw / Privilege Escalation
Affected Functionality: User Invitation & Account Registration System
Detailed Vulnerability Description
1. Vulnerability Discovery
While testing the privilege escalation mechanisms on admin.alwaysdata.com, I investigated the account invitation system. The process involves:
- Creating an account using my primary email: akashghoshakg19@gmail.com
- Inviting a secondary email: akashghoshakg19+6@gmail.com (Gmail alias)
2. Unexpected Behavior Observed
After sending the invitation, I deleted the invitation before the secondary email accepted it. However, the invitation link remained functional, allowing the secondary account (akashghoshakg19+6@gmail.com) to successfully register.
How can i sure that
Well, when i deleted my secondary account (akashghoshakg19+6@gmail.com),it sends an confirmation email to my main accout (akashghoshakg19@gmail.com) which shows in the attached video POC.
3. Impact Analysis
- Bypass of Email Verification: The system does not properly invalidate deleted invitations, allowing unauthorized account creation.
- Unrestricted Account Proliferation: An attacker can exploit this flaw to create multiple accounts without proper validation checks.
- Potential Abuse Scenarios:
Spamming the platform with fake accounts
Bypassing rate limits or sign-up restrictions
Conducting fraudulent activities under multiple identities
### 4. Proof of Concept (PoC)
Steps to Reproduce:
1. Register an account with: `akashghoshakg19@gmail.com`
2. Invite a secondary email: `akashghoshakg19+6@gmail.com`
3. Delete the invitation before the secondary user accepts it.
4. Observe that the invitation link still works, allowing `akashghoshakg19+6@gmail.com` to register.
5. Check the primary email (`akashghoshakg19@gmail.com`) – it receives a confirmation, but the system fails to enforce proper validation.
Evidence:
The video POC link: https://drive.google.com/file/d/1VmByRPCRfixrQvDWKmMnRO9KAJjT2GzB/view?usp=sharing
Security Impact
- Privilege Escalation Risk: Attackers can create multiple accounts without proper verification.
- Account Takeover Potential: If combined with other flaws, this could lead to unauthorized access.
- System Abuse: Malicious users can exploit this to evade detection and launch attacks.
Recommendations for Fix
1. Immediate Invalidation of Deleted Invitations:
Ensure that once an invitation is deleted, the associated link is immediately invalidated.
2. Strict Session & Token Validation:
Implement server-side checks to verify invitation status before allowing registration.
3. Rate Limiting & Monitoring:
Enforce stricter rate limits on account creation to prevent mass exploitation.
4. Email Verification Enforcement:
Require fresh verification for all invited accounts, regardless of invitation status.
Conclusion
This vulnerability allows bypassing critical security checks in the account registration process, leading to privilege escalation and potential system abuse. Immediate remediation is recommended to prevent exploitation.
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