Threat intelligence company Greynoise says it has observed the first attempts to exploit a recent critical remote code execution (RCE) vulnerability in Citrix ShareFile.
A popular cloud-based file-sharing and collaboration solution, ShareFile allows users to store files in their own data centers, via a storage zones controller (or storage center), a .NET web application running under Internet Information Services (IIS).
The vulnerability, tracked as CVE-2023-24489 (CVSS score of 9.1), was the result of errors leading to unauthenticated file upload, which could then be exploited to obtain RCE, says attack surface management firm Assetnote, which identified and reported the bug.
According to the cybersecurity firm, there are between 1,000 and 6,000 internet-accessible ShareFile instances, potentially making it a popular target for attackers, given that it might store sensitive data.
“Although the [vulnerable] endpoint is not enabled in all configurations, it has been common amongst the hosts we have tested. Given the number of instances online and the reliability of the exploit, we have already seen a big impact from this vulnerability,” Assetnote says.
Citrix patched the flaw in June 2023 with the release of ShareFile storage zones controller version 5.11.24, warning that it could lead to full application compromise.
“A vulnerability has been discovered in the customer-managed ShareFile storage zones controller which, if exploited, could allow an unauthenticated attacker to remotely compromise the customer-managed ShareFile storage zones controller,” the company said in an advisory.
In early July, Assetnote published proof-of-concept (PoC) code targeting the vulnerability, and additional PoC exploits have since been released, increasing the likelihood of in-the-wild exploitation.
Now, Graynoise has created a tag for CVE-2023-24489, to track in-the-wild exploitation, and the first exploit attempts were logged earlier this week.
“GreyNoise has observed IPs attempting to exploit this vulnerability. Two have never seen GreyNoise before this activity,” the threat intelligence firm says.
Citrix ShareFile customers using storage zones controllers are advised to update their installations as soon as possible.