Pierluigi Paganini March 01, 2017

More than 1 million WordPress website are at risk due to a critical SQL injection vulnerability in the NextGEN Gallery plugin. Update it asap.

Security experts at Sucuri firm have identified a SQL injection flaw in the WordPress image gallery NextGEN Gallery that could be exploited by a remote to gain access to the targeted website’s backend, including sensitive data such as passwords and secret keys.

Hackers can trigger the flaw to access the database and steal sensitive data, including passwords and secret keys.

“While working on the WordPress plugin NextGEN Gallery, we discovered a severe SQL Injection vulnerability. This vulnerability allows an unauthenticated user to grab data from the victim’s website database, including sensitive user information.” reads the analysis published by Sucuri.

The WordPress plugin NextGEN doesn’t validate the user input, for this reason, the development team has fixed the bug releasing the version 2.1.79.

“From the source code, we notice the $container_ids string is created from tag input and its values are not properly sanitized. They are safe from SQL injection but wouldn’t prevent arbitrary format string directives/input from being inserted, which may cause issues with the WordPress database abstraction prepare() method.” noticed the experts.

According to the analysis published by the security firm, there are two different attack scenarios for the exploitation of the flaw:

• The website administrator uses a NextGEN Basic TagCloud Gallery on the website. In this scenario, the attacker can execute SQL queries by modifying the URL of the gallery.
• The website administrator allows users to submit posts to be reviewed (contributors). In this case, an authenticated attacker can execute malicious code via shortcodes.

An unauthenticated attacker could add extra sprintf/printf directives to the SQL query and exploit the $wpdb->prepare’s behavior to add its code to the executed query.

The researchers also shared some examples of the final attack payloads that would look like the following ones:

http://target.url/2017/01/17/new-one/nggallery/tags/test%251%24%25s))%20or%201=1%23

http://target.url/2017/01/17/new-one/nggallery/tags/test%251%24%25s))%20or%201=2%23

The good news is that the flaw in the NextGEN Gallery hasn’t been exploited in the wild, but it is easy to predict a spike in the number of attacks leveraging the flawed plugin.

The flaw in the NextGEN Gallery is very serious due to the huge number of websites that use it, the popular WordPress image gallery plugin has more than 1 million active installations.

WordPress continues to be a privileged target for hackers, a critical flaw patched in WordPress in January has been exploited against a large number of websites.

Once again … Never trust the input!

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Pierluigi Paganini

(Security Affairs – NextGEN Gallery, WordPress)