How a Security Breach Turned a DDoS Protection Firm into an Attack Vector

Introduction

For years, Brazilian ISPs faced a relentless wave of massive DDoS attacks that seemed impossible to trace. Security researchers eventually uncovered the source: the attackers had compromised the very company that was supposed to protect those networks. Huge Networks, a Miami-founded DDoS mitigation firm serving Brazilian ISPs, had its infrastructure hijacked. The attackers gained root access through exposed SSH keys, then used that access to build a powerful botnet and launch devastating attacks. This guide explains step-by-step how the attack unfolded, based on the evidence found in an exposed archive containing malicious Python scripts and the CEO's private authentication keys. Whether you're a security professional or just curious, understanding these steps highlights the critical need for robust security even in defensive companies.

How a Security Breach Turned a DDoS Protection Firm into an Attack Vector — Source: krebsonsecurity.com

What You Need

Compromised SSH keys – the attackers obtained the CEO's private SSH keys from an exposed archive.
Malicious Python scripts – written in Portuguese, designed to automate scanning and exploitation.
Access to a DDoS protection firm's infrastructure – specifically root access to servers used for normal operations.
Scanner for vulnerable devices – to mass-scan the internet for insecure routers and misconfigured DNS servers.
DNS reflection tools – to craft spoofed queries that amplify attack traffic.
Botnet command & control – to coordinate tens of thousands of compromised devices.
Knowledge of DNS amplification – understanding how to exploit open DNS resolvers and the EDNS0 extension.

Step-by-Step Guide

Step 1: Breach the DDoS Protection Firm's Infrastructure

The attackers first needed to gain unauthorized access to Huge Networks' systems. An archive found in an open directory contained private SSH authentication keys belonging to Huge Networks' CEO. Using these keys, the threat actor logged into the company's servers with root privileges. This gave them unrestricted control over the very infrastructure that was designed to defend against DDoS attacks. The archive also included several Python malware programs – likely custom-developed for the campaign – which automated many of the subsequent steps. Without this initial breach, the entire operation would have been impossible.

Step 2: Mass-Scan the Internet for Vulnerable Devices

Once inside, the attackers used the compromised servers to launch widespread scanning of the internet. They specifically targeted two types of devices: insecure Internet routers (e.g., those with default passwords or open management interfaces) and unmanaged DNS servers that would respond to any query from anywhere on the web. The scanning was routine and continuous, building a list of thousands of potential members for the botnet. Many routers in Brazilian homes and small businesses were vulnerable, and many ISPs misconfigured their own DNS servers, leaving them open to abuse.

Step 3: Build a Botnet from Compromised Devices

After identifying vulnerable routers, the attackers exploited their weaknesses to install malware or change configurations. Each compromised device became a bot – a remote-controlled participant in the attack network. Similarly, any DNS server that was misconfigured to accept queries from the entire internet was noted as a usable amplifier. The Python scripts in the archive likely handled the exploitation and enrollment of these devices. Over time, the botnet grew to tens of thousands of nodes, all under the command of the attacker controlling Huge Networks' infrastructure.

Step 4: Launch DDoS Attacks Using DNS Reflection and Amplification

With the botnet in place, the attackers executed the final stage: massive DDoS attacks against Brazilian ISPs. They used a technique called DNS reflection. The attacker sends a DNS query that appears to come from the target's IP address (spoofing) to an open DNS resolver. That resolver then sends its response to the target, not the attacker. When this is done with the amplification enabled by the EDNS0 extension, a tiny query (under 100 bytes) can trigger a response 60-70 times larger. By sending spoofed queries from thousands of botnet devices simultaneously and using many vulnerable DNS servers, the attackers could flood their targets with enormous amounts of traffic, overwhelming their networks.

Step 5: Maintain and Conceal the Operation

Although not explicitly detailed in the report, the attackers likely took steps to maintain their access and avoid detection. The CEO claimed the malicious activity resulted from a security breach and suspected a competitor was trying to tarnish the company's image. Whether true or not, the attackers clearly had root access for an extended period, enabling them to continue the campaign. They may have rotated IP addresses, used encryption, or cleaned logs. However, the eventual exposure of the archive by a security source (an anonymous tip) ended the stealth of the operation.

Tips for Prevention and Defence

Secure SSH keys and credentials – Never store private keys in unsecured online directories. Use key managers, encryption, and rotate keys frequently.
Monitor for unauthorized access – Implement intrusion detection and log analysis to spot unusual SSH logins or internal scanning activity.
Harden network devices – Disable remote management on routers where not needed, change default passwords, and keep firmware updated.
Close open DNS resolvers – DNS servers should only accept queries from trusted networks. Check for misconfigurations that allow amplification attacks.
Segment critical infrastructure – Even defending firms should isolate their internal systems from the internet-facing ones. Root access should require multi-factor authentication.
Plan for the worst – Assume a breach is possible. Have incident response procedures ready and regularly audit third-party access.
Collaborate with researchers – The attack was uncovered by a security researcher. Publicly sharing threat indicators helps everyone defend better.

Remember: Any company that positions itself as a defender must itself be a fortress. The Huge Networks case shows that complacency can turn a shield into a sword.

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