WordPress 4.2.2 was released on Thursday to address a serious DOM-based cross-site scripting (XSS) vulnerability that has been actively exploited.
The existence of the security hole was brought to light on Wednesday by researchers at Sucuri. The vulnerability exists in the genericons icon font package and it affects plugins and themes that use this package if the “example.html” file is present.
The security firm has determined that the vulnerability impacts the JetPack plugin, which has over 1 million active installs, and the TwentyFifteen theme, which is installed by default.
Malicious actors can exploit the flaw to execute arbitrary code and hijack affected WordPress website if they can trick administrators into clicking on their exploit links.
Fixing the vulnerability is not a difficult task. All WordPress website administrators need to do is delete the “example.html” file from the genericons package. After learning that the vulnerability was being actively exploited, Sucuri reached out to major hosting providers and instructed them to virtually patch the flaw in order to protect users.
WordPress has included its own fix for the vulnerability in WordPress 4.2.2, a security and maintenance release.
“The Genericons icon font package, which is used in a number of popular themes and plugins, contained an HTML file vulnerable to a cross-site scripting attack,” WordPress wrote in a blog post. “All affected themes and plugins hosted on WordPress.org (including the Twenty Fifteen default theme) have been updated today by the WordPress security team to address this issue by removing this nonessential file. To help protect other Genericons usage, WordPress 4.2.2 proactively scans the wp-content directory for this HTML file and removes it.”
WordPress said the issue was brought to its attention by Robert Abela of Netsparker.
WordPress 4.2.2 also includes hardening for a potential XSS vulnerability when using the visual editor, and a comprehensive fix for a critical stored XSS that can be exploited to compromise websites via comments. The latest version also resolves a total of 13 functionality and performance bugs.
Credentials leak campaign
Zscaler researchers on Thursday reported spotting a campaign in which malicious actors have compromised multiple WordPress website in an effort to steal their users’ credentials. The compromised websites contain a backdoor designed to harvest credentials and send them back to the attackers.
“When unsuspecting users attempt to login to one of the compromised WordPress sites, they are served injected JavaScript code as part of the login page,” Zscaler wrote in a blog post.
Researchers have identified 18 websites that have been hijacked in this campaign, but they haven’t been able to determine the initial vector of compromise.
Netherlands-based security firm Fox-IT has noted that the attacks analyzed by Zscaler are part of the CryptoPHP campaign, which they analyzed last year.
*Updated to clarify that the attacks spotted by Zscaler are part of the CryptoPHP campaign