A recent technical report by Lumen Technologies has revealed that the China-nexus cyber espionage group known as Volt Typhoon has exploited a recently disclosed high-severity security vulnerability affecting Versa Director. The attacks began as early as June 12, 2024, targeting four U.S. entities and one non-U.S. organization within the Internet service provider, managed service provider, and information technology sectors. This ongoing campaign takes advantage of a security flaw identified as CVE-2024-39717, which has a CVSS score of 6.6 and allows unauthorized file uploads through compromised administrator accounts, ultimately exposing these systems to further exploitation.
The exploited vulnerability allows attackers to upload malicious files disguised as PNG images via the Versa Director interface, specifically through the “Change Favicon” feature. This issue has been compounded by inadequate security practices among impacted customers, who failed to implement system hardening and firewall guidelines established by Versa in previous years. The security breach has led to the deployment of a custom-tailored web shell known as VersaMem, which is designed to intercept and harvest credentials from compromised systems. This exploitation illustrates Volt Typhoon’s strategy of targeting vulnerable networks to gain access and control over downstream customers’ networks, facilitating a potential large-scale supply chain attack.
Volt Typhoon’s operations reflect a broader trend of cyber espionage, characterized by sophisticated techniques that include the use of compromised small office and home office devices. The modular nature of the VersaMem web shell enables threat actors to inject additional Java code directly into the memory of the exploited servers, enhancing their ability to execute arbitrary commands without detection. By intercepting authentication credentials, the attackers can exploit legitimate access to infiltrate further into the networks of their ultimate targets, showcasing the complexity and danger posed by this threat actor.
In response to this sophisticated attack, cybersecurity experts are advising organizations to implement crucial mitigations, such as blocking external access to specific ports associated with the vulnerability and conducting thorough scans for anomalous network traffic. Furthermore, there are reports that 163 instances of Versa Director remain exposed and publicly accessible on the internet, which increases the urgency for organizations to segment these devices within secure networks. While some claims have surfaced alleging that Volt Typhoon may be a construct of U.S. intelligence efforts, the ongoing threat posed by this advanced persistent threat highlights the critical need for heightened vigilance and robust security measures across the affected sectors.
Reference:
