What is a Sensitive Data Exposure Vulnerability?

Imagine that you receive an email from your favorite service provider saying that there was an attempt to access your account.

Or a phishing email in your inbox on behalf of your boss, with lots of information to demonstrate that it was really written by him.

Or you observe in your logs a massive attempt to break into your login using an existing non-standard user (how did they know…).

Does the story ring a bell?

Nowadays, the attacks with the best cost/success ratio are those using sensitive data leaked, like usernames + passwords, that we tend to reuse in several services; or private information to convince victims of phishing or multilevel attacks.

And this data leaked comes normally from social engineering and leveraging of vulnerabilities.

So, today we are going to talk about the Sensitive Data Exposure vulnerability type, which occurs when a WordPress site unintentionally reveals confidential information to unauthorized parties.

This can include user credentials (e.g., usernames, database credentials, passwords, backup files), personally identifiable information, a.k.a. PII (e.g., names, physical or email addresses, phone numbers), financial records, or any data meant to remain private. But also information that can be used to attack others (e.g., using phishing techniques) or as part of a multilevel attack. It is also considered a sensitive data leak when you tamper with an LLM to reveal confidential information used during its training.

Why is Sensitive Data Exposure a Concern for WordPress Users?

When sensitive data is exposed on a WordPress site, the ramifications can be severe:

• User Trust Erosion: Visitors and customers may lose confidence in your site’s ability to protect their information.
• Financial Implications: Data breaches can lead to financial losses due to fraud or legal penalties.
• Compliance Violations: Failing to safeguard data may result in non-compliance with regulations like GDPR or CCPA, and others that will soon emerge in the regulatory space, like, for example, DORA, NIS2, or CRA in Europe. Check enforcementtracker.com to get an idea of the fines being applied due to GDPR non-compliance.
• Brand Damage: The reputation of your brand can suffer, affecting mid/long-term deals.

How Does Sensitive Data Exposure Occur in WordPress?

Several factors contribute to sensitive data exposure within the WordPress ecosystem:

• Outdated Plugins and Themes: Security flaws in outdated software can be exploited to access sensitive data. There are a lot of examples within recent history of sensitive information leaked, from the case of getting IPs logged in a system from a plugin for sending emails, or accessing media that is in the trash.
• Insecure Coding Practices: Plugins or themes that don’t follow secure coding standards may inadvertently expose data through vulnerabilities like SQL injection or insecure direct object references.
• Excessive Data Sharing: In API-based scenarios, we can be sharing more information than required, relying on filtering by the frontend or user.
• Improper File Permissions: Incorrect server configurations can make sensitive files and directories publicly accessible.For example, if the “wp-config.php” is accessed due to any other vulnerability (like Path transversal one), this leads to an immediate leak of all database content (credentials to access it are set in this file), which also includes, for example, the URLs to all your site’s media, so they can be leaked as well.
• Unsecured Logs: A lot of useful information for attackers is logged in files on a WordPress site. It can be used in a multilevel attack, which is a type of attack where multiple steps are required, each using the information from the previous ones.
• Unprotected Backups: It is common practice among non-security-aware users to save backups in the root folder of WordPress, or even in any other location with read permissions, without any kind of encryption.
• Lack of Encryption: Not using SSL/TLS encryption can allow attackers to intercept data transmitted between the user and the site.
• Default Settings: Using default settings, such as predictable admin URLs or usernames, can make it easier for attackers to target your site.

What about WordPress core?

WordPress itself has had several episodes of controversy with this type of vulnerability. Still today, there are lots of WordPress sites where you can attach “wp-json/wp/v2/users” to the URL and get a list of all users of the site with lots of details, so you can then use them to brute-force the login.

Also, in a recent version, it was possible to get the URL of posts not published under certain conditions (CVE-2023-5692).

Conclusion

Sensitive Data Exposure is a serious vulnerability that can have devastating effects on your WordPress site and its users, but it is also a common cause of big fines.

By understanding how these exposures occur and taking proactive steps to secure your site—such as keeping software updated, enforcing strong security practices, and monitoring for vulnerabilities—you can protect your data and maintain the trust of your audience. Remember, website security is not a one-time setup but an ongoing process that requires vigilance and regular maintenance.