Attackers have been attempting to exploit a highly critical vulnerability in a third-party Drupal module. The flaw was addressed two months ago, but many website administrators have apparently still not applied the patches.
The vulnerability affects the RESTful Web Services (RESTWS) module, which enables developers to expose Drupal entities as RESTful web services. Versions prior to 7.x-2.6 and 7.x-1.7 allow an anonymous attacker to send specially crafted requests and execute arbitrary PHP code on targeted websites.
The issue, reported by Devin Zuczek, was one of the three Drupal module vulnerabilities resolved on July 13. A proof-of-concept (PoC) exploit and a Metasploit module were released soon after.
The SANS Institute’s Internet Storm Center reported seeing attempts to exploit the vulnerability. The organization’s honeypots detected 44 exploit attempts coming from 16 different IP addresses on Wednesday.
According to Johannes B. Ullrich, the CTO of the SANS Internet Storm Center, the exploits are simply designed to display a string, which indicates that the attackers might be trying to find vulnerable systems.
Ullrich said they had been seeing exploitation attempts since July, but previous versions of the payload were using a slightly different test.
An analysis of the IP addresses responsible for the attacks revealed that most of them are associated with Drupal websites that have likely been compromised and are now being used to scan the web for other potential targets.
“In my quick sampling, I didn’t find any obvious malicious content on these sites. I would have expected some advertisement or maybe even malware, but maybe they are still building out their network,” Ullrich explained.
Drupal vulnerabilities are often targeted by cybercriminals, even long after they have been patched. Sucuri reported recently that a flaw patched nearly two years ago, dubbed “Drupalgeddon,” is still being exploited to hack websites.