Security Experts:

SQL Injection Flaw Found in Popular WordPress SEO Plugin

The WordPress SEO by Yoast plugin is plagued by a blind SQL injection vulnerability that can be exploited to execute arbitrary SQL queries on a targeted website.

WordPress SEO by Yoast is a search engine optimization plugin installed on more than 1 million websites. UK-based researcher Ryan Dewhurst discovered the security hole on Tuesday and reported it to Yoast on the same day.

According to the expert, the vulnerability can be leveraged by an authenticated attacker for SQL injection attacks.

“The authenticated Blind SQL Injection vulnerability can be found within the 'admin/class-bulk-editor-list-table.php' file. The orderby and order GET parameters are not sufficiently sanitised before being used within a SQL query,” Dewhurst wrote in an advisory.

Since anti-CSRF protection is no present, a remote attacker can execute arbitrary SQL queries on a targeted WordPress website by tricking an authenticated administrator, editor or author into clicking on a specially crafted link.

“One possible attack scenario would be an attacker adding their own administrative user to the target WordPress site, allowing them to compromise the entire web site,” the researcher explained.

The vulnerability affects WordPress SEO by Yoast version 1.7.3.3 and prior. Fortunately, the developer addressed the issue on Wednesday with the release of versions 1.7.4 and 1.5.3 (premium version). Users are advised to update their installations.

“Frankly, that's a great response to a problem that could have put users at risk. It's brilliant that Dewhurst believes in responsible disclosure, and it's a terrific turnaround from Yoast,” commented security expert Graham Cluley, who first reported on the existence of the bug.

Dewhurst is the creator of WPScan, the open-source WordPress vulnerability testing tool. In September 2014, the expert announced the launch of the WPScan Vulnerability Database, which currently stores the details of more than 1,700 unique flaws affecting WordPress, plugins, and themes.

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.