An unknown threat cluster has targeted European healthcare organizations, deploying PlugX and ShadowPad. In some cases, these intrusions resulted in the use of ransomware called NailaoLocker.
Orange Cyberdefense CERT’s Green Nailao campaign targeted a newly patched security flaw (CVE-2024-24919, CVSS score: 7.5) in Check Point network gateway products. The attacks occurred from June to October 2024.
The technical report said, “The campaign relied on DLL search-order hijacking to deploy ShadowPad and PlugX – two implants often associated with China-nexus targeted intrusions.”
The initial access gained by exploiting vulnerable Check Point instances allowed the attackers to obtain user credentials and access the VPN with a valid account.
In the next stage, The attackers used remote desktop protocol (RDP) to explore the network and gain higher privileges. They then executed a legitimate file (“logger.exe”) to load a malicious DLL (“logexts.dll”), which installs a new version of ShadowPad malware.
Threat actors attempted to steal data by accessing the file system and creating ZIP archives. They used Windows Management Instrumentation (WMI) to send three files: a legitimate executable signed by Beijing Huorong Network Technology Co., Ltd (“usysdiag.exe”), a loader called NailaoLoader (“sensapi.dll”), and NailaoLocker (“usysdiag.exe.dat”).
Figure 5: Ransom note example left by NailaoLocker
The DLL file is sideloaded using “usysdiag.exe” to decrypt and launch NailaoLocker, a C++ ransomware. It encrypts files, adds a “.locked” extension, and leaves a ransom note asking for payment in Bitcoin or contact via a Proton Mail address.
Orange suspects a Chinese-aligned threat actor is involved due to the use of the ShadowPad implant, DLL side-loading techniques, and similar ransomware tactics linked to another group called Bronze Starlight. To read the full report clickhere.