Millions of WordPress sites were attacked this week, said Defiant, the company behind the Wordfence firewall.
The sudden rise of attacks happened when hackers discovered and began exploiting a 0day vulnerability in “File Manager, A WordPress plugin used on more than 700.000 websites.
0day allowed an attacker to upload malicious files to a website running an older version of File Managers.
It is not known how they discovered 0day, but all last week the hackers started looking for sites that had this add-on installed.
If the scan was successful, the attackers took advantage of the 0day and uploaded a web shell disguised as an image file to the victim's server. So they could access the site by adding it to a botnet.
The attacks started slowly, but intensified throughout duration of last week. Defiant detected attacks against 1 million WordPress sites as of Friday, September 4th.
In all, Defiant has blocked attacks on more than 1,7 million websites since September 1, when the attacks were first discovered.
The good news is that his team of developers File Manager created and released an update for 0day the same day it learned about the attacks. Some admins immediately installed the update, but as usual, there are others who didn't.
