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sila.ozeren@picussecurity.com (Sıla@Resources-2
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A new report has revealed that the Silver Fox APT group, a China-based state-sponsored actor active since 2024, is targeting the public sector through trojanized medical software. The group, also known as Void Arachne or The Great Thief of Valley, is known for cyber espionage, data theft, and financially motivated intrusions, targeting healthcare organizations, government entities, and critical infrastructure. Their campaigns involve a custom remote access trojan called Winos 4.0 (ValleyRAT), derived from the Gh0st RAT malware family.
The Silver Fox APT employs a multi-stage campaign that utilizes backdoored medical software and cloud infrastructure to deploy remote access tools, disable antivirus software, and exfiltrate data from healthcare and public sector targets. One confirmed case involves a trojanized MediaViewerLauncher.exe, disguised as a Philips DICOM Viewer. This trojanized binary acts as a first-stage loader, initiating the malware chain. The group also exploits popular applications like Chrome, VPN clients, deepfake tools, and voice changers with backdoored installers, distributed through phishing or poisoned search results.
Once executed, the malware reaches out to an Alibaba Cloud Object Storage bucket to retrieve an encrypted configuration file (i.dat), containing URLs and filenames for second-stage payloads disguised as benign media files (e.g., a.gif, s.jpeg). These payloads then deploy DLL loaders, anti-virus evasion logic, and a vulnerable driver (TrueSightKiller) to disable security software. The group also uses PowerShell exclusions to suppress Defender scans and employs RPC-based task creation and BYOVD techniques to terminate processes like MsMpEng.exe (Windows Defender). In a separate campaign, Silver Fox is also targeting Taiwan via phishing emails with malware families HoldingHands RAT and Gh0stCringe, using fake tax lures and PDF documents.
References :
The Silver Fox APT employs a multi-stage campaign that utilizes backdoored medical software and cloud infrastructure to deploy remote access tools, disable antivirus software, and exfiltrate data from healthcare and public sector targets. One confirmed case involves a trojanized MediaViewerLauncher.exe, disguised as a Philips DICOM Viewer. This trojanized binary acts as a first-stage loader, initiating the malware chain. The group also exploits popular applications like Chrome, VPN clients, deepfake tools, and voice changers with backdoored installers, distributed through phishing or poisoned search results.
Once executed, the malware reaches out to an Alibaba Cloud Object Storage bucket to retrieve an encrypted configuration file (i.dat), containing URLs and filenames for second-stage payloads disguised as benign media files (e.g., a.gif, s.jpeg). These payloads then deploy DLL loaders, anti-virus evasion logic, and a vulnerable driver (TrueSightKiller) to disable security software. The group also uses PowerShell exclusions to suppress Defender scans and employs RPC-based task creation and BYOVD techniques to terminate processes like MsMpEng.exe (Windows Defender). In a separate campaign, Silver Fox is also targeting Taiwan via phishing emails with malware families HoldingHands RAT and Gh0stCringe, using fake tax lures and PDF documents.
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References :
- Resources-2: Picus Security blog discussing Silver Fox APT targeting public sector via trojanized medical software.
- securityonline.info: The post appeared first on .
Classification:
- HashTags: #APT #cyberespionage #malware
- Company: Picus Security
- Target: Public Sector
- Attacker: Silver Fox
- Product: Medical Software
- Feature: Trojanized Medical Software
- Malware: HoldingHands RAT, Gh0stCringe
- Type: Espionage
- Severity: Major