Hundreds of WordPress Sites Infected By Recently Discovered Backdoor

Malware that exploits unpatched vulnerabilities in 30 different WordPress plugins has infected hundreds if not thousands of sites and may have been in active use for years, according to a writeup published last week. Ars Technica reports: The Linux-based malware installs a backdoor that causes infected sites to redirect visitors to malicious sites, researchers from security firm Dr.Web said. It's also able to disable event logging, go into standby mode, and shut itself down. It gets installed by exploiting already-patched vulnerabilities in plugins that website owners use to add functionality like live chat or metrics-reporting to the core WordPress content management system. "If sites use outdated versions of such add-ons, lacking crucial fixes, the targeted web pages are injected with malicious JavaScripts," Dr.Web researchers wrote. "As a result, when users click on any area of an attacked page, they are redirected to other sites." Searches such as this one indicate that more than 1,300 sites contain the JavaScript that powers the backdoor. It's possible that some of those sites have removed the malicious code since the last scan. Still, it provides an indication of the reach of the malware. "If one or more vulnerabilities are successfully exploited, the targeted page is injected with a malicious JavaScript that is downloaded from a remote server," the Dr.Web writeup explained. "With that, the injection is done in such a way that when the infected page is loaded, this JavaScript will be initiated first -- regardless of the original contents of the page. At this point, whenever users click anywhere on the infected page, they will be transferred to the website the attackers need users to go to." The researchers found two versions of the backdoor: Linux.BackDoor.WordPressExploit.1 and Linux.BackDoor.WordPressExploit.2. They said the malware may have been in use for three years.

Read more of this story at Slashdot.