Critical Flaw in Web Analytics Plugin Exposes WordPress Websites

WordPress website administrators who use the WP Slimstat Web analytics plugin are advised to update the application as soon as possible. The plugin is plagued by a serious vulnerability that can be exploited to hack into a site’s database.

WP Slimstat uses a secret key to encrypt data between the client and the server. The problem, according to researchers at Sucuri, is that the secret key is a hash of the plugin’s installation timestamp and it can be easily cracked with a bruteforce attack.

An attacker can use services like the Internet Archive to determine the year in which the targeted website was launched. Researchers noted that once the year is identified, an attacker has to test roughly 30 million values, a task that a modern CPU can accomplish within 10 minutes.

“The only piece missing to be able to bruteforce the site’s timestamp is valid, signed, information coming from the plugin to compare our generated signatures with. It’s used in multiple places within the host site, including its home page, making the process much easier to find,” Marc-Alexandre Montpas, senior vulnerability researcher at Sucuri, explained in a blog post.

After further investigation, researchers discovered that the flaw can be exploited for blind SQL injection attacks. A malicious actor could leverage the bug to gain access to usernames, password hashes, WordPress secret keys, and other information stored in the website’s database.

The vulnerability affects WP Slimstat 3.9.5 and earlier. The issue has been addressed in version 3.9.6. With the release of WP Slimstat 3.9.6, in addition to patching the flaw, the developer has taken further steps to protect users against SQL injection attacks.

“The security of our users’ data is our top priority, and for this reason we tightened our SQL queries and made our encryption key harder to guess. If you are using a caching plugin, please flush its cache so that the tracking code can be regenerated with the new key. Also, if you are using Slimstat to track external websites, please make sure to replace the tracking code with the new one available under Settings > Advanced,” the developer noted.

WP Slimstat has been downloaded from the official WordPress website more than 1.3 million times.

It’s important that users update their installations because it’s not uncommon for WordPress plugin vulnerabilities to be exploited in the wild. Earlier this month, Sucuri reported that cybercriminals had injected malicious iframes into numerous WordPress sites by exploiting a zero-day in the FancyBox plugin.