RondoDox Botnet: How Hackers Are Turning TBK DVRs and Four-Faith Routers into Stealthy DDoS Weapons

Imagine this: the security camera system you installed years ago in your retail store or warehouse—the one you rarely think about—has quietly become part of a global cyber army. Not for your benefit, but for hackers wielding a new, highly evasive botnet called RondoDox. This isn’t a scene from a sci-fi movie; it’s unfolding right now, and if you rely on digital video recorders (DVRs) or routers from brands like TBK or Four-Faith, your devices could already be drafted into the fight.

In this article, I’ll walk you through how RondoDox operates, why it’s targeting these overlooked devices, and—most importantly—what you can do to protect yourself and your organization. If you’re responsible for IT, security, or just curious about the evolving threat landscape, this is a story you can’t afford to skip.

Why IoT Devices Like DVRs and Routers Are the Newest Cyber Battleground

Let’s get personal for a second: when was the last time you updated the firmware on your security camera DVR or checked the firewall settings on your office router? If you’re like most small business owners or IT managers, the answer is “not recently”—and cybercriminals are counting on that.

The Problem with Forgotten Tech

Longevity: Devices like TBK DVRs and Four-Faith routers are built to last, often running for years without attention.
Exposure: Many are directly connected to the internet for convenience, but this makes them accessible to anyone—including hackers.
Neglect: Regular security checks and updates are rare, giving attackers a wide window of opportunity.

Here’s why that matters: When devices go unmonitored, they become low-hanging fruit for cybercriminals. These “set-and-forget” systems are being actively probed and exploited right now, often without their owners ever knowing until it’s too late.

Meet RondoDox: The Botnet That’s Redefining Stealth Attacks

So, what exactly is RondoDox? In simple terms, it’s a new breed of malware that links together compromised IoT devices—like DVRs and routers—into a botnet. But unlike older botnets, RondoDox is designed to be especially sneaky, resilient, and hard to detect.

What Makes RondoDox Different?

Advanced Evasion: It disguises its network traffic as popular games or VPN platforms, making malicious activity look legitimate.
Multi-Device Targeting: RondoDox can infect a wide variety of devices running Linux, thanks to multi-architecture support.
Persistence: Once installed, it can survive reboots and actively fights off attempts to remove it.
Stealth Proxy Use: Instead of just launching attacks, it uses your device as a relay point—to hide hackers’ real identities or amplify attacks.

In other words, RondoDox doesn’t just take over your device—it drafts it into a cybercriminal army that’s built for stealth and longevity.

The Flaws That Let RondoDox In: What You Need to Know About CVE-2024-3721 and CVE-2024-12856

Now, let’s get into the specifics. How does RondoDox get inside your devices in the first place? It exploits two main vulnerabilities:

CVE-2024-3721: TBK DVR Command Injection

Devices Affected: TBK DVR-4104 and DVR-4216 (commonly used in surveillance systems)
Threat: This flaw allows attackers to execute system commands remotely, essentially giving them full control over the device.
Severity: Rated medium, but in practice it can be devastating if exploited.

CVE-2024-12856: Four-Faith Router OS Command Injection

Devices Affected: Four-Faith F3x24 and F3x36 routers (often found in industrial and commercial settings)
Threat: Similar to above, attackers can remotely issue commands, completely compromising the router.

Both of these vulnerabilities have been widely publicized and are being actively targeted in the wild. If your devices are running outdated firmware, you’re at risk—plain and simple.

For more on these vulnerabilities, check out MITRE’s CVE database.

How RondoDox Hijacks Devices: A Step-by-Step Breakdown

Let’s peek under the hood at the RondoDox playbook. Understanding the attack chain can help you spot potential warning signs.

1. Exploitation

Attackers scan the internet for vulnerable TBK DVRs and Four-Faith routers, using automated tools to find devices with outdated, unpatched firmware.

2. Multi-Architecture Dropper Infection

The malware first identifies the device’s architecture (ARM, MIPS, Intel, etc.).
It uses a shell script downloader to fetch the right version of the RondoDox payload.
The dropper instructs the system to ignore standard termination signals, making it tough to kill the process.

3. Establishing Persistence

RondoDox installs itself in writable directories such as /var/tmp or /dev/shm.
It ensures the malware automatically restarts after a reboot, maintaining long-term control.

4. Clearing Tracks

The script erases command history to hide its presence.
It renames common recovery and network tools (e.g., iptables, ufw, passwd) to random strings, making manual recovery hard for IT teams.

Here’s an example of how important commands get renamed:

5. Command and Control (C2) Communications

Once set up, the malware connects to an external command server (e.g., 83.150.218[.]93).
Instructions are encoded, often using XOR encryption, to evade detection by security tools.

6. Launching Attacks

Devices are used to launch Distributed Denial-of-Service (DDoS) attacks via HTTP, UDP, and TCP.
The traffic mimics games like Minecraft, Fortnite, and tools like OpenVPN or Discord, blending into normal network activity.

Why RondoDox Is So Hard to Detect

This isn’t an ordinary botnet. RondoDox was designed to outsmart both IT defenders and traditional security tools. Here’s how:

1. Camouflage by Emulation

RondoDox can make its malicious traffic look like it’s coming from:

Popular online games (Valve, Roblox, DayZ, Fortnite, GTA)
VPN and chat services (Discord, OpenVPN, WireGuard)
Real-time communication protocols (STUN, DTLS, RTC)

This makes network monitoring tools less likely to flag suspicious activity because it blends in with normal traffic patterns.

2. Anti-Analysis and Stealth

Kills Security Tools: It searches for and terminates running processes like Wireshark, wget, curl, gdb, and even other malware.
Encrypts Configurations: Key data is XOR-encoded and stored in custom-built libraries, complicating forensic analysis.
Persistence: By renaming executables and clearing logs, RondoDox frustrates manual cleanup efforts.

3. Multi-Architecture Support

Unlike many older botnets, RondoDox isn’t picky. It can run on almost any Linux-based device, from the humble ARM chip in a DVR to the beefier Intel CPUs in industrial routers.

The Bigger Picture: How RondoDox Fits Into the Modern Threat Landscape

RondoDox is just one example of a growing category: next-generation Linux malware that targets the “Internet of Things” (IoT). Others like Mozi and RustoBot exploit the same weaknesses—poor device hygiene, weak passwords, and outdated firmware.

Why Attackers Love IoT Devices

Sheer Numbers: There are billions of vulnerable IoT devices worldwide.
Weak Defenses: Many lack robust security controls or regular updates.
Critical Roles: These devices often control physical security, manage networks, or handle sensitive data.
Difficult Detection: Many organizations never monitor them closely.

The bottom line? If your device can connect to the internet, it can be recruited into a botnet—unless you take steps to secure it.

What’s at Stake: Real-World Risks of a Botnet Takeover

This isn’t just a theoretical risk. Here’s what could happen if your TBK DVR or Four-Faith router gets compromised by RondoDox:

DDoS Participation: Your device could flood other victims with junk traffic, slowing or taking down critical services.
Stealth Proxy: Attackers can use your device to relay commands, hiding their real location and identity.
Infrastructure Disruption: If enough devices in a supply chain are compromised, entire networks can be crippled.
Financial Fraud: DDoS attacks are often linked to extortion and scams, costing businesses millions.

And worst of all? You may never know your device was involved—until law enforcement or your ISP comes knocking.

How to Protect Your Devices from RondoDox (and Similar Threats)

Let’s shift from doom and gloom to action. What can you do to keep your DVRs, routers, and other IoT devices safe?

1. Patch and Update Immediately

Check for Firmware Updates: Visit the manufacturer’s website for your TBK DVR or Four-Faith router.
Apply Security Fixes: Both CVE-2024-3721 and CVE-2024-12856 have patches or mitigation advice. Update as soon as possible.

2. Harden Device Security

Change Default Passwords: Never leave factory credentials unchanged.
Disable Unused Services: Turn off any network services you don’t need (e.g., Telnet, UPnP).
Lock Down Ports: Only open ports absolutely necessary for operation. Use network segmentation where possible.

3. Monitor and Audit

Network Monitoring: Monitor for strange traffic spikes or unfamiliar device communication.
Log Review: Regularly check logs for unauthorized access or process renaming.
Inventory Devices: Make a list of all connected devices and ensure each is regularly reviewed.

4. Consider Network Segmentation

Isolate IoT Devices: Place critical devices on separate VLANs or networks from sensitive data or business systems.
Use Firewalls: Restrict outbound traffic from IoT devices unless absolutely necessary.

5. Prepare an Incident Response Plan

Have Backups: Keep regular backups of configurations and settings.
Know How to Recover: Be prepared to reset devices and restore from clean sources if compromise is detected.

If you’re unsure where to start, CISA’s IoT Security Guidance is a valuable resource.

RondoDox in Context: The Ongoing Evolution of Botnets

As cybercriminals get more sophisticated, so do their tools. RondoDox demonstrates several key trends:

Stealth Over Noise: Modern malware focuses on blending in, not just brute force.
Persistence and Recovery Inhibition: Techniques to survive reboots and sabotage recovery are becoming standard.
Multi-Architecture Reach: Attacks are no longer limited by hardware diversity.

And perhaps most importantly, the lines between criminal hacking and large-scale infrastructure disruption are blurring. Botnets like RondoDox can be rented out for DDoS-for-hire, used in financial scams, or even (potentially) leveraged for geopolitical sabotage.

Frequently Asked Questions (FAQ)

What is the RondoDox botnet?

RondoDox is a malware-based botnet that infects Linux-based IoT devices—especially TBK DVRs and Four-Faith routers—using unpatched security vulnerabilities. It converts these devices into stealthy proxies and DDoS attack tools.

Which devices are at risk from RondoDox?

Primarily TBK DVR-4104/4216 and Four-Faith F3x24/F3x36 routers, but any unpatched Linux device with similar vulnerabilities could be targeted.

How does RondoDox avoid detection?

It disguises its network activity as legitimate traffic (e.g., games, VPNs), encrypts command data, disables security tools, and renames common recovery utilities.

What should I do if I think my device is infected?

Immediately disconnect the device from the network.
Factory reset and reflash the firmware with the latest version.
Change all passwords and review network logs for suspicious activity.

Can RondoDox infect Windows or Mac devices?

No, RondoDox currently targets Linux-based systems, most commonly found in DVRs, routers, and embedded IoT devices.

Where can I find official patches and guidance?

The Takeaway: Don’t Let Your Device Become a Cybercriminal’s Secret Weapon

The age of “set and forget” is over—especially when it comes to internet-connected cameras and routers. RondoDox is a wake-up call: even the most unassuming devices on your network can be recruited into global botnets that threaten businesses, infrastructure, and even national security.

If you own or manage TBK DVRs, Four-Faith routers, or any Linux-based IoT device: – Update your firmware now. – Change default credentials. – Monitor for strange activity. – Implement robust network segmentation.

Staying vigilant isn’t just about protecting your own systems—it’s about safeguarding the internet for everyone. Curious about the latest in IoT security and threat research? Subscribe to our blog or check out more expert insights here and here.

Stay safe, stay informed, and never underestimate the devices quietly ticking away on your network. They may be doing more than you think.

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