Account Activation Token Prediction in Pie Register WordPress Plugin

Executive Summary

The Pie Register WordPress plugin before version 3.8.4.10 has a vulnerability where it generates account verification tokens using predictable values based on the server's timestamp (md5(time())).

Because these tokens are not sufficiently random, unauthenticated attackers can predict valid tokens within a small time window.

This allows attackers to activate user accounts without having access to the associated email inbox, effectively bypassing the email verification process.

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Impact Analysis

This vulnerability can allow attackers to activate accounts without verifying ownership of the associated email address.

As a result, unauthorized users could gain access to accounts or services that require email verification, potentially leading to unauthorized access or abuse of the system.

It undermines the authentication process and could facilitate further attacks or misuse of the affected WordPress site.

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Detection Guidance

This vulnerability can be detected by attempting to predict account activation tokens generated by the Pie Register plugin prior to version 3.8.4.10. Since the tokens are generated using md5(time()), an attacker can capture the server time, compute possible tokens within a small time window, and test these tokens against the activation endpoint to see if any are valid.

A practical approach involves monitoring HTTP requests to the activation endpoint and checking for token patterns that match md5 hashes of recent timestamps.

Suggested commands might include using curl or wget to test token values against the activation URL, for example:

• Use a script to generate md5 hashes of timestamps around the current time.
• Use curl to send requests to the activation endpoint with these tokens, e.g., curl "https://example.com/activate?token=<generated_token>"
• Analyze server logs for repeated activation attempts with predictable tokens.

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Mitigation Strategies

The immediate step to mitigate this vulnerability is to update the Pie Register WordPress plugin to version 3.8.4.10 or later, where the token generation method was fixed to use a stronger and more secure function (wp_generate_password(32, false)) instead of predictable md5(time()).

Until the update can be applied, consider monitoring and restricting access to the account activation endpoint to prevent unauthorized token guessing.

Additionally, review and enhance logging and alerting for suspicious activation attempts.

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Compliance Impact

This vulnerability allows unauthenticated attackers to bypass email verification by predicting account activation tokens, enabling account activation without access to the associated email inbox.

Such unauthorized account activation could lead to unauthorized access to user accounts and potentially sensitive personal data.

This situation may impact compliance with standards and regulations like GDPR and HIPAA, which require protection of personal data and secure authentication mechanisms to prevent unauthorized access.

Specifically, the vulnerability relates to broken authentication and insufficient cryptography, which are critical controls in these regulations to ensure data confidentiality and integrity.

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