The Hidden Backdoor: How a Junior Hacker Outsmarted Traditional Security Measures
In the world of cybersecurity, we often focus on the flashy, high-profile attacks orchestrated by advanced persistent threats (APTs). But what happens when a junior hacker, armed with nothing but free tools and a bit of ingenuity, manages to outsmart traditional security measures? This is the story of 'Poisson,' a French-speaking attacker whose recent intrusion into a small automotive business offers a masterclass in persistence and lateral thinking.
The Unassuming Intruder
What makes this case particularly fascinating is how Poisson, despite being a novice, managed to maintain access to the victim’s network even after his command-and-control (C2) server went offline. Personally, I think this highlights a critical blind spot in many organizations’ security strategies: the assumption that taking down a C2 server is enough to stop an attack. Poisson’s use of OpenSSH and Tailscale to create a separate backdoor is a stark reminder that attackers often have multiple ways in—and out.
From my perspective, the most intriguing aspect of this attack is how Poisson leveraged legitimate tools to achieve his goals. Tailscale, a secure mesh VPN, and OpenSSH, a widely used remote access protocol, are not inherently malicious. What many people don’t realize is that these tools, when misused, can become powerful weapons in the hands of even inexperienced attackers. This raises a deeper question: how do we detect and mitigate the misuse of legitimate tools without disrupting normal operations?
The Persistence Playbook
One thing that immediately stands out is Poisson’s persistence mechanism. By installing OpenSSH and Tailscale, he created a backdoor that operated independently of his C2 server. This move was not just clever—it was forward-thinking. When the Havoc C2 infrastructure went offline, his access remained intact. If you take a step back and think about it, this is a game-changer for how we approach incident response. Pulling the plug on a C2 server is no longer enough; we need to actively hunt for these hidden persistence layers.
A detail that I find especially interesting is how Poisson’s tradecraft was far from perfect. He leaked his home directory multiple times, named storage buckets after his own handle, and even left a test file of his keystrokes. Yet, despite these mistakes, he still managed to compromise four machines. What this really suggests is that even attackers with limited skills can cause significant damage if they exploit the right tools and techniques.
The Broader Implications
This case also underscores a troubling trend: the democratization of cybercrime. Poisson operated on a shoestring budget, using free-tier services like DuckDNS and Backblaze B2. In my opinion, this is a wake-up call for the cybersecurity community. As tools become more accessible, the barrier to entry for cybercrime continues to lower. We’re no longer just fighting nation-state actors; we’re up against anyone with a computer and an internet connection.
What makes this particularly fascinating is how Poisson’s tactics align with those of more advanced groups. China’s APT31, for example, has used Tailscale to tunnel out of Russian IT firms, while Scattered Spider has relied on legitimate remote-access tools like Ngrok. The binaries are signed and legitimate, which means traditional detection methods that focus on malicious files are ineffective. This raises a deeper question: are we focusing too much on detecting malware and not enough on detecting anomalous behavior?
Lessons for Defenders
Cato Networks’ analysis provides a concrete hunting list for defenders, but I think the bigger lesson here is mindset. When you find a C2 server, assume it’s not the only way in. Attackers like Poisson are increasingly using layered persistence mechanisms to ensure they can regain access even if their primary infrastructure is taken down. This requires a shift from reactive to proactive defense—constantly hunting for signs of compromise rather than waiting for alerts.
Personally, I believe this case also highlights the need for better behavioral analytics. Tools like OpenSSH and Tailscale are legitimate, but their misuse should trigger red flags. For instance, the installation of OpenSSH on a Windows workstation is rarely legitimate, and reverse SSH tunnels to external hosts should always be investigated. What many people don’t realize is that these anomalies are often easier to detect than malicious files, but they require a different approach to monitoring.
The Unanswered Questions
One of the most intriguing aspects of this case is what Poisson was ultimately after. Unlike many attackers who deploy ransomware or exfiltrate sensitive documents, Poisson focused narrowly on stealing banking logins, email passwords, and government portal credentials. In my opinion, this suggests a financially motivated attacker, but it also raises questions about his endgame. Was he planning to sell these credentials on the dark web, or was there a larger scheme at play?
Another unanswered question is the purpose of the two executables from Thales.zip that ran for 32 minutes on the victim’s machine. Cato Networks left this detail open, but it’s a critical piece of the puzzle. If you take a step back and think about it, those 32 minutes could have been used for anything from data exfiltration to lateral movement. Without knowing what those programs did, we can’t fully understand the scope of the intrusion.
Final Thoughts
Poisson’s attack is a reminder that cybersecurity is not just about technology—it’s about thinking like an attacker. His use of legitimate tools, layered persistence, and narrow focus on high-value credentials demonstrates a level of creativity that many defenders underestimate. From my perspective, this case should serve as a wake-up call to reevaluate our assumptions about what constitutes a threat and how we respond to it.
In the end, what this really suggests is that the battle against cybercrime is not just about tools and tactics—it’s about mindset. Defenders need to adopt a more proactive, hunter-like approach, constantly questioning and investigating anomalies. Because, as Poisson’s case shows, the backdoor is often hidden in plain sight.
