Less than 24 hours after Joomla released patches for a couple of critical account creation vulnerabilities, researchers noticed that malicious actors had already started exploiting the flaws in the wild.
Joomla announced on October 25 the availability of version 3.6.4 to fix two serious vulnerabilities: CVE-2016-8870, which allows attackers to create user accounts even if account registration is disabled, and CVE-2016-8869, a privilege escalation that allows hackers to gain administrator rights. A combination of these flaws can be exploited to upload a backdoor and gain complete control of vulnerable Joomla websites.
While Joomla developers made public only very limited information about the vulnerabilities, it was easy for researchers and threat groups to identify the problematic code and develop exploits.
Researchers at Sucuri said they spotted attempts to exploit the flaws in the wild shortly after the patches were released. The first attacks, launched within 24 hours, targeted some of the most popular Joomla sites and their goal was to create user accounts.
Later, Sucuri noticed the first mass exploitation attempts coming from three IP addresses in Romania. The attackers had been trying to create an account with the username “db_cfg” and the password “fsugmze3” on thousands of Joomla sites. An IP address from Latvia was also observed launching similar attacks.
The volume of attacks increased even more after researchers started sharing exploits, including ones that automatically uploaded a backdoor to vulnerable sites. On October 28, Sucuri reported observing more than 27,000 infections, but the actual number is likely much higher.
“Some of [the exploits] are even automating the upload of backdoors and using some unique techniques to bypass the media uploader (using .pht files),” explained Daniel Cid, founder and CTO of Sucuri.
The security firm believes all websites that haven’t been patched immediately are likely already compromised. Joomla website administrators have been advised to check their logs for activity from the IP addresses identified by Sucuri, and look for any suspicious admin accounts.