The U.S. Department of Justice (DoJ) and Federal Bureau of Investigation (FBI) have disrupted two hacking platforms operated by a China-linked threat group that were used to conduct reconnaissance, compromise vulnerable systems and conceal attacks against U.S. government agencies, critical infrastructure and other sensitive organizations.
The platforms, QScan and QTRouter, have been attributed to QTFY, a Chinese state-sponsored hacking group linked to Nanjing Xinjiuwei Network Technology Company. According to U.S. authorities, QTFY activity has targeted organizations including NASA, the Federal Reserve, Department of Energy, Department of Justice, Department of Health and Human Services, National Institutes of Health and the U.S. Senate.
Lumen Black Lotus Labs, which tracked the infrastructure for more than 18 months, said QTFY activity dates back to at least May 2018. The researchers described the group as an infrastructure "quartermaster" that developed reusable systems for reconnaissance, exploitation and traffic obfuscation.
QScan automated reconnaissance and exploitation
QScan formed the reconnaissance component of the operation. The platform scanned internet-connected systems and IoT devices for vulnerabilities before automatically compromising susceptible devices and incorporating them into the QTRouter network.
The FBI said QScan was also used to identify vulnerabilities in victim networks. Its infrastructure included servers responsible for distributing scanning tasks to worker nodes and collecting completed results.
The scale of the operation allowed QTFY to conduct reconnaissance across large numbers of systems. Lumen identified scanning activity spanning more than 130 countries, with targets including government, defense, aerospace, healthcare, financial, energy and research organizations.
QTRouter concealed attackers' origins
Compromised devices identified through QScan were subsequently used by QTRouter as proxy nodes. The network combined hacked IoT devices with commercial proxy services and leased virtual private servers (VPSs), allowing malicious traffic to pass through multiple intermediary systems.
This architecture made an intrusion originating from China appear to come from an internet connection located elsewhere. In some cases, QTRouter could route traffic through systems geographically close to the targeted organization, making the activity appear more consistent with legitimate local traffic.
QTRouter operated on routers running customized OpenWrt software and used the Clash proxy framework to establish connections. Operators could select available nodes and chain them together, creating multiple layers between themselves and their targets.
The FBI said this combination of compromised IoT devices and legitimate commercial proxy infrastructure made malicious traffic difficult to distinguish from normal internet activity.
Attackers exploited new and older vulnerabilities
QTFY's attack chain involved both recently disclosed and long-standing vulnerabilities. The vulnerabilities identified by investigators included flaws in Ivanti Connect Secure, Fortinet SSL-VPN, Citrix ADC, Microsoft Exchange Server, F5 BIG-IP, Kentico CMS, Apache Log4j, Atlassian Confluence, Check Point Quantum Gateway, CrushFTP and BeyondTrust Remote Support.
After obtaining initial access, QTFY actors used remote access trojans, web shells and legitimate credentials to maintain persistence.
The infrastructure could subsequently provide concealed access into victim networks through nearby compromised IoT devices. QTBotnet also allowed operators to control infected systems, execute commands and conduct distributed denial-of-service attacks.
Four-part infrastructure supported QTFY operations
Lumen identified QScan and QTRouter as part of a larger architecture that also included Fast Labyrinth and QTProxy.
Fast Labyrinth incorporated commercial proxy infrastructure into encrypted relay paths, while QTProxy managed operational nodes and allowed operators to configure routes toward selected targets.
The researchers compared the architecture to an operational relay box, or ORB, network. Such systems use compromised devices and leased infrastructure as rotating relay points, making traditional IP blocklists and location-based defenses less effective.
Lumen said the infrastructure demonstrated an increasingly industrialized model of China-linked cyber operations, in which reusable and shared services can provide reconnaissance and anonymity at global scale.
FBI seized domains used by the platforms
The disruption targeted domains hard-coded into QScan and QTRouter, including infrastructure used to distribute scanning tasks and administer proxy connections.
By seizing these domains through court-authorized action, U.S. authorities disrupted communication between the platforms and their operators, causing the systems to cease functioning.
Investigators also linked QTFY to Chinese cyber-brokering networks where exploits, malware and access to
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