CYBERCRIME SYNDICATES

BlackTech Unmasked

Inside the Decade-Long Cyber Espionage Campaign Targeting East Asia and the US

21 min readApr 12, 2025

In the shadowy realm of cyberspace, nation-state actors constantly refine their techniques to infiltrate networks, steal sensitive information, and gain strategic advantages. Among the most persistent and sophisticated players is a group tracked under various aliases: BlackTech, Palmerworm, Temp.Overboard, Circuit Panda, Radio Panda, and cataloged by MITRE ATT&CK® as G0098. Active since at least 2010, and possibly as early as 2013 according to some sources, this suspected Chinese state-sponsored cyber espionage group has carved a niche for itself through stealth, persistence, and a particular knack for burrowing deep into the network infrastructure of its targets.

This group isn’t just another flash in the pan; they represent a long-term, evolving threat. Their targets span critical sectors — media, construction, engineering, electronics, finance, technology, telecommunications, government, and the defense industrial base — primarily located in East Asia (notably Taiwan, Japan, and Hong Kong) and the United States. Their objective? Classic espionage: stealing intellectual property, sensitive data, and potentially gaining insights into strategic operations.

What sets BlackTech apart is their methodical approach and mastery of blending in. They employ a potent cocktail of custom-built malware, readily available dual-use tools, and “living off the land” (LotL) techniques, making detection a significant challenge. Perhaps most distinctively, BlackTech has demonstrated an advanced capability to compromise and manipulate network routers, turning trusted infrastructure components into hidden backdoors and command posts.

This post aims to provide a comprehensive deep dive into the world of BlackTech. We will explore their history, dissect their intricate Tactics, Techniques, and Procedures (TTPs), examine their bespoke malware arsenal, analyze their signature router manipulation techniques, discuss the evidence pointing towards state sponsorship, and outline crucial defensive strategies. Understanding BlackTech isn’t just an academic exercise; it’s essential for any organization operating within their target scope or concerned about sophisticated persistent threats.

Origins and Evolution — A Decade of Stealthy Operations

BlackTech’s activities first came into focus for security researchers around 2010–2013. From the outset, their targeting patterns suggested a focus on espionage rather than financial gain or disruption. Early campaigns zeroed in on organizations in Taiwan, Japan, and Hong Kong, regions of significant strategic interest to the People’s Republic of China (PRC).

Early analysis, notably by Trend Micro in 2017, began connecting seemingly disparate campaigns — PLEAD, Shrouded Crossbow, and Waterbear — suggesting they might be orchestrated by the same entity, or at least closely collaborating teams under the BlackTech umbrella. This conclusion was based on shared Command and Control (C2) infrastructure, overlapping targets, and similarities in tools and techniques, such as the use of Right-to-Left Override (RTLO) character tricks (T1036.002) to disguise malicious file types and the deployment of small loaders for encrypted backdoors.

Over the years, BlackTech has demonstrated a continuous evolution, adapting its toolset and techniques to bypass evolving security measures. They moved from exploiting older vulnerabilities like CVE-2012–0158 (Microsoft Office) and CVE-2015–5119 (Adobe Flash) to leveraging newer ones and refining their custom malware. Symantec noted a significant campaign spanning 2019–2020 that introduced a fresh suite of previously undocumented backdoors (Consock, Waship, Dalwit, Nomri), indicating ongoing development efforts.

A defining characteristic that has become more prominent in recent reporting, particularly highlighted in a joint advisory (AA23–270A) by CISA, NSA, FBI, and Japanese cybersecurity agencies (NPA, NISC) in September 2023, is BlackTech’s focus on network devices, specifically routers. This indicates a strategic shift or refinement, focusing on gaining persistent access at the network edge, exploiting trust relationships, and creating highly covert communication channels.

Their sustained activity over more than a decade, coupled with continuous malware development and adaptation of TTPs, underscores their status as a well-resourced and persistent threat actor, consistent with the profile of a state-sponsored espionage group.

Targetology — Following the Strategic Interest

BlackTech’s choice of targets provides significant clues about their motives and suspected sponsors. The consistent focus on organizations in Taiwan, Japan, Hong Kong, and the United States aligns closely with the known strategic, economic, and political interests of the People’s Republic of China.

Taiwan: A primary focus since BlackTech’s emergence. Taiwan’s unique political status, advanced technology sector (especially semiconductors), and democratic institutions make it a perennial target for PRC intelligence gathering across political, military, and industrial domains. Media companies in Taiwan have also been specifically targeted, potentially for monitoring narratives or identifying sources.
Japan: Another key target, particularly in the technology, engineering, defense, and government sectors. Japan is a major economic competitor, a key US ally in the region, and possesses advanced technology that is likely of interest for industrial espionage. Recent advisories explicitly mention Japanese headquarters being targeted via compromised international subsidiaries.
United States: Targets include US companies, particularly those with subsidiaries in East Asia, and entities supporting the US military. The goal here likely involves stealing intellectual property from technology and defense companies, understanding US policy and military positioning in the region, and potentially gaining access to US corporate networks via less secure international branches.
Hong Kong: Targeted especially in earlier years, likely related to monitoring pro-democracy movements, media outlets, and financial institutions.

The targeted sectors further illuminate their objectives:

Technology & Electronics: Stealing intellectual property, R&D data, semiconductor designs, and proprietary technologies. Reports mention major electronics companies being infiltrated.
Engineering & Construction: Gaining insights into infrastructure projects, proprietary designs, and potentially sensitive government contracts.
Media: Monitoring news narratives, potentially identifying sources, or using compromised media outlets for future influence operations.
Finance: Accessing financial data, understanding economic trends, or potentially compromising financial institutions for strategic economic intelligence.
Government & Defense Industrial Base: Classic espionage goals — stealing classified information, understanding military capabilities and readiness, accessing government communications, and gaining insights into policy decisions. Entities supporting the US and Japanese militaries are explicitly mentioned as targets.
Telecommunications: Compromising telecom providers can offer broad access to communications data and serve as infrastructure for further attacks.

This deliberate and sustained targeting pattern strongly supports the hypothesis that BlackTech operates in support of PRC state interests, focusing on intelligence collection and technology acquisition.

The BlackTech Playbook — A Deep Dive into Tactics, Techniques, and Procedures (TTPs)

BlackTech employs a comprehensive and evolving set of TTPs, meticulously mapped by organizations like MITRE ATT&CK®. Their approach emphasizes stealth, persistence, and leveraging existing system functionalities.

Initial Access (TA0001): Gaining a Foothold

BlackTech uses several methods to breach target networks:

Spear-Phishing (T1566): This is a common vector. They send emails with malicious attachments (T1566.001) often disguised using Right-to-Left Override (RTLO) (T1036.002) to make executable files look like documents. Attachments might be password-protected archives (ZIP, RAR) containing malware. They also use emails with malicious links (T1566.002), potentially directing victims to cloud services to download malware.
Exploiting Public-Facing Applications (T1190): BlackTech has exploited known vulnerabilities in web servers like Microsoft IIS (e.g., CVE-2017–7269) and client-side software like Microsoft Office (CVE-2012–0158, CVE-2014–6352, CVE-2017–0199) and Adobe Flash (CVE-2015–5119) (Exploitation for Client Execution — T1203).
Compromising Edge Routers: As detailed later, they target routers, potentially exploiting vulnerabilities or using stolen credentials to gain initial access to network edge devices.
Supply Chain Attacks (Implied): While not explicitly detailed as an initial vector in all reports, compromising routers at subsidiary locations or potentially hijacking legitimate software updates (as seen with related groups like Evasive Panda targeting QQ updates, or BlackTech’s own past compromise of ASUS WebStorage updates to deliver Plead) represents a supply chain risk. One report mentions exploiting an anti-virus update function at a Chinese branch office to infiltrate headquarters.

Execution (TA0002): Running Malicious Code

Once initial access is achieved, BlackTech executes its payloads using methods like:

User Execution (T1204): Relying on the user to click a malicious link (T1204.001) or open a malicious file (T1204.002).
Exploitation for Client Execution (T1203): Triggering vulnerabilities in client software.
Native API (T1106): Using built-in operating system functions to run code.
Command and Scripting Interpreter (T1059): Using shells like Windows Command Shell (T1059.003) or potentially PowerShell (T1059.001) although specific BlackTech PowerShell use needs confirmation. Flagpro malware uses Visual Basic (T1059.005).

Persistence (TA0003): Staying Embedded

BlackTech excels at maintaining long-term access:

Router Firmware Modification: Installing modified firmware on routers (particularly Cisco IOS) containing backdoors (like SSH backdoors — T1556.004) and disabling logging (T1562.003). This is a key, high-stealth technique.
Registry Modifications (T1112): Modifying Windows registry keys for autostart (Boot or Logon Autostart Execution — T1053.005 via Registry Run Keys / Startup Folder) or enabling services like RDP (T1021.001).
Scheduled Tasks/Jobs (T1053): Creating scheduled tasks to execute malware periodically.
Implant Custom Malware: Deploying their range of backdoors (Waterbear, PLEAD, Flagpro, etc.).
SSH Backdoors: Beyond routers, potentially using SSH (T1021.004) for persistent access on compromised hosts.
Netcat Shells: Establishing simple, persistent command shells.

Privilege Escalation (TA0004): Gaining Higher Rights

To facilitate deeper access and lateral movement, BlackTech seeks elevated privileges:

Exploiting Vulnerabilities: Using exploits that grant system-level access.
Abusing Legitimate Mechanisms: Techniques like DLL Side-Loading (T1574.002) can sometimes lead to privilege escalation if a legitimate high-privilege process loads a malicious DLL.
Credential Access: Stealing administrator credentials grants elevated rights. Gaining administrator access on network edge devices is noted as a precursor to firmware modification.

Defense Evasion (TA0005): Avoiding Detection

Stealth is paramount for BlackTech:

Router Firmware Manipulation: Hiding activity within the router’s modified OS, disabling logging (T1562.003), bypassing security features.
Stolen Code-Signing Certificates (T1588.003): Signing malware with legitimate, stolen certificates to bypass security software checks (Masquerading — T1036, specifically Code Signing — T1553.002). They also use stolen digital certificates (T1588.004).
DLL Side-Loading (T1574.002): Placing malicious DLLs with expected names in directories searched by legitimate applications, causing the application to load the malicious code.
Living Off the Land (LotL): Using standard system tools and protocols (see Chapter 6) to blend in with normal network activity, making detection by EDR and other security tools difficult.
Obfuscated Files or Information (T1027): Using techniques like RTLO (T1036.002), encrypting payloads, using junk data, or encoding files.
In-Memory Execution: Malware like BendyBear and Waterbear/Deuterbear operate extensively in memory to avoid file-based scanning. BendyBear uses polymorphic code. Deuterbear includes anti-memory scanning and complex decryption routines.
Disabling Security Tools (T1562): Potentially disabling or impairing defenses, including indicator blocking or removal from tools (T1562.006, T1027.005).
Proxying Traffic (T1090): Using compromised routers (T1090.002) or other infrastructure to mask C2 communications (TA0011).

Credential Access (TA0006): Stealing Logins

Accessing credentials facilitates lateral movement and deeper access:

Credentials from Password Stores (T1555): Malware like PLEAD is known to harvest saved credentials from web browsers (T1555.003) and email clients like Outlook.
Keylogging (T1056.001): Malware like KIVARS includes keylogging capabilities.

Discovery (TA0007): Mapping the Environment

Once inside, BlackTech explores the network:

Network Service Discovery (T1046): Using tools like the custom SNScan tool to find other potential targets and services on the victim network.
System Information Discovery (T1082): Gathering details about the compromised system.
Process Discovery (T1057): Listing running processes.
File and Directory Discovery (T1083): Searching for files and directories of interest.
Application Window Discovery (T1010): Identifying open application windows (seen with Flagpro).

Lateral Movement (TA0008): Spreading Across the Network

BlackTech moves strategically within compromised environments:

Exploitation of Remote Services (T1210): Using tools like PsExec (often abused via SMB/Windows Admin Shares — T1021.002).
Remote Services (T1021): Using SSH (T1021.004) via tools like Putty, or enabling/using RDP (T1021.001).
Abuse of Trust Relationships (T1199): This is critical to their router-based strategy. They pivot from compromised routers in international subsidiaries (often less secure) to headquarters networks by exploiting the inherent trust between these network segments.

Collection (TA0009): Gathering Target Data

BlackTech focuses on specific data:

Data from Local System (T1005): Collecting files from the compromised host.
Automated Collection (T1119): Using tools like DRIGO (associated with PLEAD) to specifically search for and collect documents.
Screen Capture (T1113): KIVARS has screenshot capabilities.
Keylogging (T1056.001): Capturing user keystrokes.

Command and Control (TA0011): Communicating with Implants

BlackTech uses various methods for C2:

Compromised Routers: Leveraging modified router firmware for stealthy C2 channels, proxying traffic (T1090.002) through them to blend in.
Application Layer Protocol (T1071): Using standard protocols like HTTP/HTTPS (T1071.001) for C2. Deuterbear specifically uses HTTPS. Sometimes using FTP internally (T1071.002).
Encrypted Channels (T1573): Using symmetric cryptography (T1573.001) or standard protocols like TLS for encrypted C2.
Shared Infrastructure: Reports note multiple BlackTech malware families communicating with the same C2 servers.
Potential Use of Web Services: The DRIGO tool used with PLEAD reportedly used Google Drive accounts linked via refresh tokens for exfiltration, suggesting potential C2 or data staging via legitimate services (T1071.009 — Cloud Services).

Exfiltration (TA0010): Stealing the Data

Getting the stolen data out:

Exfiltration Over C2 Channel (T1041): Sending data back through the primary C2 communication channel.
Exfiltration to Cloud Storage: The DRIGO tool linked to PLEAD used Google Drive.
Scheduled Transfer (T1029): Potentially scheduling data transfers.
Data Transfer Size Limits (T1030): Possibly breaking data into smaller chunks to avoid detection.

This intricate web of TTPs highlights BlackTech’s sophistication, adaptability, and focus on long-term, undetected access for espionage purposes.

The BlackTech Malware Arsenal — Custom Tools for Espionage

BlackTech relies heavily on a diverse and evolving set of custom malware families, often deployed in combination. Here are some of their key tools:

PLEAD (S0435): A prominent backdoor often used in initial stages. It can harvest credentials from browsers and email clients, list drives/processes/files, open a remote shell, upload/download/delete files, and execute applications. It’s often delivered via spear-phishing and uses decoy documents. PLEAD has been associated with the DRIGO exfiltration tool, which specifically targets documents and uses Google Drive for exfiltration.
Waterbear (S0579) / Deuterbear: A complex and long-standing malware family known for sophisticated evasion techniques. It often involves a multi-stage infection chain starting with DLL side-loading. The loader fetches the main RAT component from a C2 server. Waterbear has undergone significant updates, with the newer variant (dubbed Deuterbear by Trend Micro) featuring enhanced anti-memory scanning, advanced decryption routines, debugger/sandbox checking, and HTTPS C2 communications. Its complexity suggests a high level of development effort.
Flagpro (S0696): Another versatile backdoor with capabilities including web protocol communication, application window discovery, registry modification for persistence, command execution (Cmd, Visual Basic), data encoding, local data collection, credential stealing (web browsers), data obfuscation, encrypted C2, file/directory discovery, and tool transfer.
KIVARS (Backdoor.Kivars): An older backdoor associated with BlackTech. Capabilities included file download/execution, drive listing, malware uninstallation, screenshots, keylogging activation, window manipulation, and remote mouse/keyboard input. A 64-bit version was developed.
Newer Backdoors (2019–2020): Symantec identified four previously undocumented backdoors used in campaigns during this period: Consock, Waship, Dalwit, and Nomri. While specifics were limited, their emergence indicated active development and potential evolution from older tools, possibly PLEAD variants according to some vendor detections.
FakeDead / TSCookie (S0436): A backdoor with an associated downloader module known as FrontShell.
BendyBear (S0574): Described by CISA as a shellcode loader employing polymorphic code and operating primarily in memory to evade detection and analysis.
Bifrose: An older, well-known RAT family dating back to 2004, observed being used by BlackTech. Known features include remote access, keylogging, and reverse connections to bypass firewalls.
BTSDoor: Another custom malware family attributed to BlackTech.
IconDown: Mentioned as part of BlackTech’s arsenal.
Spider Suite (SpiderPig, SpiderSpring, SpiderStack): Additional custom malware families employed by the group.
Router-Specific Payloads: While not always named, BlackTech deploys custom code within modified router firmware. This code implements functionalities like SSH backdoors, magic packet checking (likely for backdoor activation), and code to bypass or disable logging features on the router itself.

This extensive and continuously updated toolkit allows BlackTech to tailor its attacks, maintain persistence, and evade detection across various operating systems (Windows, Linux, FreeBSD) and network devices. The use of multiple layers (loader, backdoor, specialized tools) and techniques like DLL side-loading and stolen code certificates are hallmarks of their operations.

Living Off the Land and Dual-Use Tools — Hiding in Plain Sight

A key element of BlackTech’s strategy for stealth and persistence is its adept use of “living off the land” (LotL) techniques and dual-use tools. By leveraging legitimate software and built-in operating system utilities, they minimize the deployment of easily detectable custom malware and blend their malicious activities with normal network traffic and administrative actions.

Why LotL?

Stealth: Activity using standard tools is less likely to trigger alerts from basic security software (like legacy antivirus) compared to custom malware signatures.
Reduced Footprint: Minimizes the amount of malicious code that needs to be deployed onto a system.
Bypassing Application Whitelisting: Legitimate tools are often implicitly trusted and allowed to run.
Attribution Difficulty: Using common tools makes it harder to definitively link activity to a specific threat group without additional correlating evidence.

BlackTech’s Known Dual-Use / LotL Toolkit:

Based on reporting from CISA, Symantec, MITRE ATT&CK®, and others, BlackTech leverages tools including:

PsExec: A legitimate Sysinternals tool often used by administrators for remote execution. BlackTech abuses it for lateral movement across networks (T1569.002 — Service Execution via PsExec).
Putty: A popular open-source SSH and Telnet client. BlackTech uses it for establishing remote access via SSH (T1021.004) and potentially for data exfiltration over the SSH channel.
WinRAR: A common file archiving utility. Attackers use it to compress stolen data before exfiltration (making it smaller and potentially easier to transfer) or to extract malicious payloads from archives delivered via phishing (T1560.001 — Archive via Utility).
SNScan: A network scanning tool used for discovery (T1046 — Network Service Discovery) to identify other potential targets or services on the compromised network.
Netcat: A versatile networking utility often used to establish simple backdoors or transfer files. CISA notes its use by BlackTech for persistence.
Remote Desktop Protocol (RDP): BlackTech has been observed modifying the registry (T1112) to enable RDP (T1021.001), allowing them graphical remote access.
Local FTP Server: CISA mentions BlackTech using a local FTP server (T1071.002 — File Transfer Protocols) likely for staging or moving data internally within the victim network before exfiltration.
Native OS Tools: While specific usage details require deeper investigation per incident, groups like BlackTech commonly abuse built-in tools like cmd.exe (T1059.003), potentially PowerShell (T1059.001), WMI (T1047 - Windows Management Instrumentation), certutil (often used for downloading files or decoding data - T1140), and bitsadmin (T1197 - BITS Jobs).

The increasing reliance on LotL tactics by APT groups like BlackTech underscores the need for defenders to move beyond signature-based detection. Monitoring how legitimate tools are used, establishing behavioral baselines, and scrutinizing command-line activity are crucial for uncovering these blended threats.

The Router Threat — Compromising the Network’s Gatekeepers

One of the most alarming and sophisticated aspects of BlackTech’s operations is their demonstrated ability to compromise and modify the firmware of network routers, particularly targeting Cisco IOS devices, although other brands may also be vulnerable. This tactic provides them with an incredibly stealthy and persistent foothold right at the network edge.

Why Target Routers?

Strategic Position: Routers sit at critical network junctions, handling traffic between internal segments, subsidiaries, and the internet. Control over a router provides significant visibility and control over network traffic.
Implicit Trust: Routers within an organization, especially those connecting branch offices to headquarters, often operate under established trust relationships (T1199). Firewalls might have less stringent rules for traffic originating from a “trusted” internal router compared to external sources.
Persistence: Firmware modifications can survive device reboots and are often outside the scope of standard endpoint security solutions. Re-imaging or replacing hardware might be the only way to fully eradicate the compromise.
Stealth: Security logging and monitoring are often less mature on network devices compared to servers and workstations. BlackTech specifically modifies firmware to disable or bypass logging (T1562.003), effectively erasing their tracks at the device level.
Infrastructure: Compromised routers become part of BlackTech’s operational infrastructure, used for proxying C2 traffic (T1090.002) and pivoting to other targets.

How BlackTech Modifies Router Firmware (Based on CISA Advisory AA23–270A):

The process observed on Cisco IOS routers is highly sophisticated:

Gain Privileged Access: BlackTech actors first gain administrative control over the target router, likely through exploiting vulnerabilities or using stolen credentials (TA0004).
Install Older Legitimate Firmware (Optional but Observed): Sometimes, they may first install an older, legitimate version of the firmware (T1601.002 — Downgrade Attack), possibly one with known vulnerabilities or less robust security features that facilitates the next steps.
Hot Patching: They modify the router’s running firmware image in memory. This “hot patch” temporarily bypasses security checks that would normally prevent the loading of unsigned or modified firmware.
Install Modified Bootloader: Using the temporary bypass, they install a modified bootloader.
Install Malicious Firmware: The modified bootloader then allows the installation of the custom, malicious firmware image containing BlackTech’s backdoors and stealth features.
Hooking Functions: Within the malicious firmware, BlackTech hooks existing Cisco IOS functions, redirecting them to their own malicious code. This allows them to implement:

An SSH backdoor (T1556.004) for persistent remote access.
Magic packet checking (potentially for activating the backdoor).
Functionality to bypass or disable logging mechanisms (T1562.003).

Exploiting Trust Relationships (T1199):

A key goal of compromising routers, especially those in international subsidiaries or branch offices, is to abuse the trusted connection back to the corporate headquarters. By initiating connections from the compromised subsidiary router, BlackTech traffic might bypass security controls that would scrutinize traffic originating from the external internet. This allows them to pivot laterally from a potentially less secure subsidiary environment into the more sensitive core network of the headquarters in the US or Japan.

This focus on manipulating network infrastructure itself represents a significant escalation in stealth and persistence, making detection and remediation extremely challenging for targeted organizations.

Attribution — Following the Trail to the PRC

Attributing cyberattacks, especially those conducted by sophisticated state-sponsored actors, is inherently complex and often relies on a convergence of evidence rather than a single smoking gun. However, the consensus among cybersecurity researchers and government agencies points strongly towards BlackTech being linked to the People’s Republic of China (PRC).

Key indicators supporting this attribution include:

Targeting Alignment: As discussed earlier, BlackTech’s consistent targeting of specific sectors (technology, defense, government, media) and geographic regions (Taiwan, Japan, US, Hong Kong) aligns directly with the known strategic intelligence and economic espionage objectives of the PRC.
Official Statements: Government bodies have increasingly made direct attributions.
Taiwanese officials have publicly stated their belief that BlackTech is backed by the Chinese government.
The joint advisory AA23–270A issued in September 2023 by CISA, NSA, FBI (USA) and NPA, NISC (Japan) explicitly identifies BlackTech as “PRC-linked cyber actors.” Such public, multi-national attribution carries significant weight.
Reported Overlaps: Some security reports, like a 2019 analysis by Macnica, suggested potential overlaps or coordinated activity involving BlackTech (referred to as Huapi in that report) and another suspected Chinese APT group, Tick (also known as Nian), in targeting major Japanese electronics companies. While group overlaps can be complex, this suggests potential resource sharing or common tasking within a larger state apparatus.
Sophistication and Resources: The group’s longevity (active over a decade), continuous development of complex custom malware (Waterbear/Deuterbear, firmware modifications), use of zero-day vulnerabilities (historically), and ability to acquire and use stolen code-signing certificates all point to a level of resources and operational sustainment typically associated with state sponsorship.
Espionage Focus: BlackTech’s activities are overwhelmingly focused on intelligence gathering and data theft, rather than financial crime or disruptive attacks, which is characteristic of state-sponsored espionage operations.

While Symantec, in its 2020 report, refrained from direct geographic attribution, it acknowledged the Taiwanese government’s assessment linking BlackTech to the PRC. The cumulative evidence, particularly the strong alignment of targets with PRC interests and the direct attribution in joint government advisories, leads to high confidence within the cybersecurity community that BlackTech is a PRC state-sponsored entity.

Defense and Mitigation — Protecting Against a Stealthy Adversary

Defending against a sophisticated and stealthy actor like BlackTech requires a multi-layered, defense-in-depth strategy focusing on visibility, hardening, and proactive threat hunting. Generic security measures are often insufficient.

Network Security & Router Hardening:

Firmware Integrity: Regularly verify the integrity of router firmware images against known good versions. Implement secure boot processes if available.
Patching: Keep router operating systems (like Cisco IOS) and other network devices patched against known vulnerabilities.
Secure Configuration: Harden router configurations: disable unnecessary services, use strong and unique credentials, implement access control lists (ACLs), restrict management access (use dedicated management networks/PAWs, enforce MFA).
Logging: Ensure comprehensive logging is enabled on network devices and forwarded to a central SIEM. Monitor logs for unusual activity, configuration changes, or attempts to disable logging. Crucially, monitor for the TTPs used to disable logging.
Network Segmentation: Implement robust network segmentation, particularly between subsidiaries/branch offices and headquarters. Scrutinize traffic flowing between trusted zones, not just at the external perimeter. Consider Zero Trust architecture principles — don’t implicitly trust traffic based on network location.
Intrusion Detection/Prevention Systems (IDS/IPS): Deploy and maintain IDS/IPS with up-to-date signatures and behavioral analysis capabilities to detect known malware C2 traffic, exploit attempts, and anomalous network behavior.
VPN Security: Ensure VPNs used for remote access meet NCSC or equivalent standards and enforce MFA.

Endpoint Security:

Endpoint Detection and Response (EDR): Deploy advanced EDR solutions capable of behavioral analysis to detect LotL techniques and memory-based threats. Standard AV is insufficient.
Patch Management: Aggressively patch operating systems and applications (especially browsers, Office, Adobe) to mitigate vulnerability exploitation.
Application Control: Use application allowlisting (e.g., AppLocker in Constrained Language mode for PowerShell) to prevent unauthorized executables and scripts from running.
Macro Security: Disable or strictly constrain Microsoft Office macros.
Credential Protection: Implement MFA for all user accounts, especially privileged ones and remote access points. Use Privileged Access Workstations (PAWs) for administrative tasks. Minimize the number of privileged accounts and practice the principle of least privilege. Regularly review and remove unnecessary permissions.

Email and Web Security:

Email Filtering: Implement robust email filtering to block malicious attachments (executable files, potentially password-protected archives) and links. Use services like NCSC’s Mail Check (if eligible) or commercial equivalents.
Web Filtering: Block access to known malicious websites and consider content inspection for downloads.
User Training: Educate users about phishing tactics, including spear-phishing, link manipulation, and the dangers of opening unexpected attachments.

Operational Practices:

Threat Intelligence: Consume threat intelligence feeds to stay updated on BlackTech TTPs, IOCs (Indicators of Compromise), and malware signatures.
Backup and Recovery: Maintain regular, tested, offline backups. Ensure backup solutions are segregated and protected with MFA.
Incident Response Plan: Have a well-defined and practiced incident response plan to quickly contain and remediate compromises.
Asset Management: Maintain an accurate inventory of hardware and software assets to facilitate rapid patching and incident scoping.
Code Signing Certificate Vigilance: Don’t automatically trust software just because it’s signed. Scrutinize the publisher reputation and be wary of recently issued certificates or those from unexpected sources.

Defeating BlackTech requires vigilance across the entire security stack, with a particular focus on network infrastructure security and monitoring for the subtle signs of LotL activity.

The Enduring Threat of BlackTech

BlackTech represents a significant and enduring cyber espionage threat, characterized by its sophistication, persistence, and dedication to stealth. Operating for over a decade with suspected PRC state backing, the group has consistently targeted high-value organizations across East Asia and the US, adapting its tools and techniques to remain effective.

Their mastery of living off the land, combined with a potent arsenal of custom malware and, most notably, their advanced capability to compromise and hide within router firmware, makes them a formidable adversary. By abusing trust relationships and blending into normal network activity, BlackTech challenges traditional security paradigms and highlights the critical need for enhanced vigilance, particularly around network infrastructure security and behavioral threat detection.

For organizations operating in targeted regions or sectors, understanding BlackTech’s playbook is not optional; it’s essential for survival. Implementing robust, layered defenses, embracing Zero Trust principles, maintaining rigorous patching and configuration management, and fostering a culture of security awareness are crucial steps.

The fight against advanced persistent threats like BlackTech is a continuous marathon, not a sprint. As they evolve, so too must our defenses. By sharing intelligence, investing in advanced security capabilities, and remaining perpetually vigilant, we can work to mitigate the risks posed by these hidden adversaries lurking within our networks.

References

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Cybersecurity and Infrastructure Security Agency. (2023, September 27). CISA, NSA, FBI and Japan release advisory warning of BlackTech, PRC-Linked cyber activity. CISA News & Events. Retrieved April 10, 2025, from https://www.cisa.gov/news-events/news/cisa-nsa-fbi-and-japan-release-advisory-warning-blacktech-prc-linked-cyber-activity

Cybersecurity and Infrastructure Security Agency (CISA), National Security Agency (NSA), Federal Bureau of Investigation (FBI), Japan National Police Agency (NPA), & Japan National Center of Incident Readiness and Strategy for Cybersecurity (NISC). (2023, September 27). People’s Republic of China-Linked Cyber Actors Hide in Router Firmware. (Advisory No. AA23–270A). [PDF Document]. U.S. Department of Defense. Retrieved April 10, 2025, from https://media.defense.gov/2023/Sep/27/2003309107/-1/-1/0/CSA_BLACKTECH_HIDE_IN_ROUTERS_TLP-CLEAR.PDF

Cybersecurity and Infrastructure Security Agency (CISA), National Security Agency (NSA), Federal Bureau of Investigation (FBI), Japan National Police Agency (NPA), & Japan National Center of Incident Readiness and Strategy for Cybersecurity (NISC). (2023, September 27). People’s Republic of China-Linked Cyber Actors Hide in Router Firmware. (Advisory Number: AA23–270A). Cybersecurity and Infrastructure Security Agency. Retrieved April 10, 2025, from https://www.cisa.gov/news-events/cybersecurity-advisories/aa23-270a

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