100,000 WordPress Sites Impacted with Cross-Site Scripting(XSS) Flaw

KingComposer, a WordPress plugin found installed with over 100,000 WordPress sites found vulnerable to Reflected Cross-Site Scripting.

The vulnerability was found by the Wordfence security team with KingComposer Drag and Drop page building plugin.

The vulnerability can be exploited by the attacker tricking the victim into clicking a malicious link, which sends the victim to the vulnerable website along with the payload.

It can be tracked as CVE-2020-15299 and received CVSS Score: 6.1. the version before 2.9.5 is affected by the vulnerability.

The vulnerability resides with AJAX action that no longer actively used by the plugin, “but could still be used by sending a POST request to wp-admin/admin-ajax.php with the action parameter set to kc_install_online_preset.”

The vulnerability can be exploited using base64-encoding on a malicious payload and trick the victim into sending a request through a kc-online-preset-data parameter, which would allow the malicious payload to execute on the victim browser.

The Wordfence Threat Intelligence detected the vulnerability on June 15, 2020, and it was patched by plugin developers on June 29, 2020.

Users are recommended to update with the latest version of the plugin to mitigate the vulnerability.

• Defenses against Cross-Site Scripting
• What input do we trust?
• Does it adhere to expected patterns?
• Never simply reflect untrusted data.
• Applies to data within our database too.
• Encoding of context(Java/attribute/HTML/CSS).

Here is the course to learn more about XSS – Cross-Site Scripting attack and for WordPress security.