WordPress has released security updates that fix three issues, including two cross-site scripting vulnerabilities and a potential privilege escalation exploit, which could have allowed potential compromise of millions of live web sites, the company reports.
WordPress, a popular PHP-based Content Management System, is the most prominent web platform on the Internet today, running over 20 percent of the top one million websites worldwide, according to some reports.
As a result, cyber criminals and malicious hackers frequently target WordPress instances to gain access to private databases and internal network access. A typical WordPress compromise is based on exploits of vulnerabilities in an outdated plug-in component and, more recently, brute force attacks on WordPress are on the rise. As Daniel Cid, founder & CTO of Sucuri Security, wrote earlier this month on his company blog:
“When you have an unprotected login page, you will see brute force attempts. With WordPress sites, the same rule applies. We see thousands of failed login attempts to /wp-login.php on the websites we protect per minute. In fact, failed login attempts jumped from 5.2 million in January to 40.9 million on Sept. 15, on sites protected behind Sucuri's firewall.”
Heimdal Security, meanwhile, has observed an increase in malicious scripts injected into legitimate websites that redirect Internet users to the Neutrino exploit kit server when accessed. The company said that the attack is “carried out by systemically compromising websites which run an outdated content management system or outdated plugins." The cyber-attack is mainly directed at websites built on WordPress, according to the company.
Today, it’s all about the core code
However, these latest vulnerabilities were in the core WordPress code. So instead of affecting 5,000 to 10,000 sites that installed a specific plug-in, there was the potential for millions of websites worldwide being compromised, says Shahar Tal, head of vulnerability research with Check Point Technologies, which discovered two of the vulnerabilities.
“So that is a different magnitude of discovery,” Tal says.
According to WordPress, version 4.3.1 addresses the following vulnerabilities, as well as fixes 26 bugs:
- WordPress versions 4.3 and earlier are vulnerable to a cross-site scripting vulnerability when processing shortcode tags (CVE-2015-5714). Reported by Shahar Tal and Netanel Rubin of Check Point.
- A separate cross-site scripting vulnerability was found in the user list table. Reported by Ben Bidner of the WordPress security team.
- Finally, in certain cases, users without proper permissions could publish private posts and make them sticky (CVE-2015-5715). Reported by Shahar Tal and Netanel Rubin of Check Point.
Attackers have built specific tools, such as scanners, to search out and exploit vulnerabilities on WordPress platforms, Tal says. “There have been countless stories where adversaries – cybercriminals or nation-state adversaries – have actively infiltrated a WordPress website for multiple reasons,” he says.
Attackers are looking for ways to move laterally throughout an organization’s network. By hacking into a company’s web server, adversaries can continue into the internal network to see what they can find. A second scenario is a watering hole attack, where an adversary can run arbitrary script code to try and infect every visitor to a website with certain malware, Tal says.
Typically a rare occurrence
Compared to the frequent findings of third-party plug-in vulnerabilities, issues with WordPress core code are rare, Tal notes. WordPress core developers are well-trained and have a high security awareness for all released code. This fact was confirmed during Check Point’s audit of the source code. Developers implement multiple layers of security protecting WordPress from most attack vectors Check Point security researchers can think of, Tal notes.
“WordPress in its core is relatively well-secured in comparison with most PHP code that you typically come across,” Tal says. PHP is a server-side scripting language designed for web development but is also used as a general-purpose programming language.
However, the security team lead by Netanel Rubin was very persistent and found several holes. The first vulnerability allowed the researchers to escalate privileges from a subscriber user with read-only privileges, to a user who could create, write and post content. A hacker could also use these privileges and create situations to perform SQL injection attacks on databases. And, then they also discovered the cross-site scripting vulnerabilities.
Check Point’s team notified WordPress and opened up discussions in which they suggested fixes and a few alternatives to address the problems, Tal says. WordPress took one of the suggested alternatives and fixed the cross-scripting vulnerabilities. The privilege escalation fix was more complicated because it touched a sensitive area of code, plus it affected third-party plug-ins and libraries. As a result, the company needed more testing before coming out with that fix, Tal notes, which is now available in WordPress 4.3.1.