Yoast has released a new version of its popular Google Analytics plugin for WordPress to address a persistent cross-site scripting (XSS) vulnerability that could have been exploited to execute arbitrary code.
Google Analytics by Yoast has been downloaded nearly 7 million times. The application allows WordPress administrators to monitor website traffic by connecting the plugin to their Google Analytics account.
The vulnerability was identified by Jouko Pynnonen, the CEO of Finland-based IT company Klikki Oy. Earlier this month, the expert reported identifying several vulnerabilities in the WPML premium WordPress plugin.
According to the researcher, an attacker can leverage a flaw in Google Analytics by Yoast to store arbitrary code in a targeted administrator’s WordPress dashboard. The code is executed as soon as the administrator opens the plugin’s settings panel.
The attack involves two security bugs. First, there is an access control flaw that allows an unauthenticated attacker to connect the plugin installed on the targeted website to his own Google Analytics account by overwriting existing OAuth2 credentials.
The second stage of the attack relies on the fact that the plugin renders an HTML dropdown menu based on data from Google Analytics. Because this data is not sanitized, an attacker can enter malicious code in the Google Analytics account and it gets executed when the targeted administrator views the plugin’s settings panel.
“Under default WordPress configuration, a malicious user can exploit this flaw to execute arbitrary server-side PHP code via the plugin or theme editors,” Pynnonen said in an advisory. “Alternatively the attacker could change the administrator’s password, create new administrator accounts, or do whatever else the currently logged-in administrator can do on the target site.”
The security issues have been addressed with the release of Google Analytics by Yoast version 5.3.3. The update also fixes a flaw that allowed administrators to launch XSS attacks against other administrators. This vulnerability was publicly disclosed back in February by Kaustubh G. Padwad and Rohit Kumar.
This isn’t the first time someone finds a vulnerability in a plugin from Yoast. Last week, UK-based researcher Ryan Dewhurst uncovered a blind SQL injection vulnerability in WordPress SEO by Yoast.