WordPress PHP Object Injection

Febna V M
Published on
05 Jun 2024
4 min read

A PHP object injection is a vulnerability that allows an attacker to perform attacks like code injection, SQL Injection, path traversal, and application Denial of Service.

WordPress PHP object injection is a type of vulnerability that can occur in a WordPress website if it improperly handles user-supplied input and deserializes it.

There are many vulnerable plugins in WordPress library that allow an attacker to perform a remote attack to the application.

These plugins can successfully exploit a system because the application failed to sanitize user-supplied input before being passed to the unsterilized PHP function.

Attackers can exploit this issue to execute malicious PHP code on this web server. Using this vulnerability, an attacker can perform attacks like code injection, SQL injection, path traversal attack and denial of service attack.

How PHP object injection works

1. Serialization and deserialization

Serialization is the process of converting an object into a storable or transmittable format.

Deserialization is the reverse process, where the serialized format is converted back into an object.

2. User input handling

If a WordPress plugin, theme, or core functionality improperly handles user input and deserializes it without proper validation, it can lead to PHP Object Injection.

3. Malicious serialized data

An attacker can craft malicious serialized data and inject it into the application. When this data is deserialized, it can create objects with properties controlled by the attacker.

What are the impacts of WordPress PHP object injection

WordPress PHP Object Injection can have severe impacts on a website, leading to a range of security issues. Here are the primary impacts:

1. Remote Code Execution (RCE)

This can allow them to take full control of the server, install backdoors, and execute malicious scripts, potentially compromising the entire hosting environment.

2. Privilege escalation

They might gain administrative access, allowing them to modify site settings, add or delete users, and access restricted content.

3. Data theft and manipulation

Sensitive information, such as user data, payment details, and confidential documents, can be stolen or altered. This can lead to data breaches and loss of trust from users.

4. Website defacement

This can damage the site’s reputation, cause loss of credibility, and impact user experience. Attackers might post offensive content, which could lead to legal and ethical issues.

5. Denial of Service

This can make the website unavailable to legitimate users, causing downtime and loss of revenue, especially for e-commerce sites.

6. Creation of malicious users

This ensures continued access even if the original vulnerability is patched. It makes it difficult to fully clean up the site without identifying and removing all unauthorized users.

7. Distribution of malware

This can lead to the site’s inclusion in blacklists by search engines and security software, drastically reducing traffic and harming the site’s reputation.

8. Server resource abuse

This can lead to the server being blacklisted, increased hosting costs, and potential legal repercussions.

How can you prevent WordPress PHP object injection vulnerabilities?

Mitigating PHP Object Injection vulnerabilities in WordPress requires a multi-faceted approach that includes secure coding practices, input validation, and regular security assessments. Here are the key strategies to mitigate this risk:

1. Code audits and reviews

Conduct regular code audits to identify and fix potential vulnerabilities, especially in plugins and themes. Use static code analysis tools to detect insecure code patterns.

2. Update and patch

Ensure WordPress core, themes, and plugins are updated regularly to the latest versions to benefit from security patches.

3. Security plugins and firewalls

Install and configure WordPress security plugins (e.g., Wordfence, Sucuri) to monitor, detect, and block malicious activities. Implement a Web Application Firewall (WAF) to filter and monitor HTTP requests.

4. Least privilege principle

Apply the principle of least privilege to user accounts. Ensure users have only the permissions necessary to perform their tasks. Regularly review and update user roles and permissions.

5. Secure coding practices

Adopt secure coding practices, such as OWASP guidelines, to minimize the risk of vulnerabilities.

Train developers on secure coding techniques and common security pitfalls.

By avoiding unsafe serialization practices, validating and sanitizing user inputs, securing deserialization processes, conducting regular code audits, keeping software updated, using security plugins, applying the principle of least privilege, and adhering to secure coding practices, you can significantly mitigate the risk of PHP Object Injection vulnerabilities in WordPress.

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Written by
Febna V M
Febna V M
Cyber Security Engineer
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