In the summer of 2024, I was doing what I usually do when I want to understand a threat: reading source code. Mirai's source had been public since 2016, leaked by its original author on HackForums. Thousands of people had read it. Security researchers had written papers about it. Law enforcement had used it in prosecutions. And yet, sitting right there in the command and control server code, was a vulnerability that nobody had reported.
That vulnerability became CVE-2024-45163. A remote, unauthenticated denial-of-service flaw that could crash any Mirai C&C server. In practical terms, a kill switch for one of the most prolific botnets in history.
I was not looking for a vulnerability. I was studying the architecture. Mirai is interesting from an operational perspective because it is remarkably well-engineered for something built by a college student to DDoS Minecraft servers. The scanner, the loader, the bot, the C&C: each component is lean and purposeful. Understanding how attackers build infrastructure teaches you a lot about how to defend against it.
I had the source open in my editor, tracing the connection handling logic in the C&C server. The C&C is written in Go, and it handles incoming connections from both bots (the infected IoT devices) and operators (the humans who control the botnet). When an operator connects, the server presents a fake terminal interface. It asks for a username and password. If the credentials are valid, the operator gets access to the attack command interface.
That is where things got interesting.
The C&C server allocates resources for each incoming connection. When a new connection arrives, the server spins up a goroutine to handle it, allocates buffers, and starts processing input. The authentication step reads the username and password from the connection. But here is the problem: the server does not enforce any limits on unauthenticated connections.
If you open a connection and never send credentials, the goroutine just sits there, waiting. The connection is alive, resources are allocated, and the server is holding state for a client that will never authenticate. Do this a few hundred times and the server runs out of resources. Do it a few thousand times and it crashes.
This is not a sophisticated attack. There is no buffer overflow, no memory corruption, no clever exploitation chain. It is a resource exhaustion bug caused by missing connection limits and timeouts on the pre-authentication path. The kind of thing that would get caught in a code review at any legitimate software company. But Mirai was not built by a legitimate software company. It was built fast, by someone who was not thinking about defensive programming for their illegal botnet controller.
I wrote a simple proof of concept to confirm the vulnerability. The script opens TCP connections to the C&C server's operator port and holds them open without sending any data. Within seconds, the C&C server becomes unresponsive. Existing operator sessions freeze. New connections are refused. The bots lose their command channel.
The entire botnet does not die. The bots themselves continue running on infected devices. But without the C&C server, no one can issue new attack commands. The botnet becomes headless. Ongoing DDoS attacks that were already in progress would continue until their duration expires, but no new attacks can be launched. For a botnet that relies on real-time operator commands, this is effectively a kill switch.
I tested this against my own lab instance, not against live infrastructure. That distinction matters. Accessing someone else's C&C server without authorization would be illegal regardless of how malicious that server is. The research was conducted entirely on infrastructure I controlled.
Disclosing a vulnerability in malware is a strange process. There is no vendor to contact. There is no bug bounty program. The "developers" are criminals. You cannot exactly open a GitHub issue on their repo.
I went through MITRE for CVE assignment and coordinated with the security research community. The CVE was assigned as CVE-2024-45163. I published the details so that defenders and law enforcement could use the information.
The disclosure raised an interesting ethical question that I spent a lot of time thinking about. When you find a vulnerability in malicious software, who are the stakeholders? The people running the botnets are criminals. The people being attacked by the botnets are victims. Law enforcement wants tools to disrupt criminal infrastructure. The disclosure calculus is completely different from finding a bug in someone's web application.
I decided that full disclosure was the right call. The vulnerability was simple enough that any competent operator could find and fix it in their fork. Withholding the information would not protect anyone, it would just mean that defenders and law enforcement could not use it either.
The response from the security community was immediate. Researchers began mapping how many active Mirai variants were still vulnerable. The answer was: most of them. Mirai's source has been forked and modified hundreds of times since the original leak, but the C&C server code is surprisingly consistent across variants. Most operators copy the C&C code with minimal changes. The same bug existed across the ecosystem.
Law enforcement agencies took notice. I cannot go into specific details about ongoing operations, but the vulnerability provided a new tool in the toolkit for disrupting botnet infrastructure. When you can take down a C&C server with a few hundred TCP connections and zero authentication, that changes the calculus of botnet takedown operations significantly.
The biggest lesson was not technical. It was about assumptions. Thousands of researchers had read the Mirai source code. Many had published detailed analyses. But most of them were focused on the bot, the scanner, the infection mechanisms. The C&C server was treated as a given, a simple piece of infrastructure that just works. Nobody was looking at it with an attacker's mindset turned inward.
Security research has a bias toward complexity. We celebrate sophisticated exploitation chains, novel attack techniques, zero-days that require deep kernel knowledge. But some of the most impactful vulnerabilities are simple. A missing timeout. An unchecked resource allocation. The kind of bug you learn about in your first semester of network programming.
The other lesson was about persistence. I was not the first person to read that code. I was not the smartest person to read that code. But I was reading it carefully, line by line, thinking about what could go wrong at each step. That is not genius. That is patience. And in security research, patience finds bugs that cleverness misses.
CVE-2024-45163 is probably the most impactful thing I have found. Not because it was technically impressive, but because the target was so significant. Mirai and its variants are responsible for some of the largest DDoS attacks in internet history. Giving defenders a simple, reliable way to disrupt that infrastructure matters. Sometimes the most important work in security is not building new defenses. It is finding the cracks in the attacker's foundation.