A Cybersecurity Close Call:
How We Detected and Contained the Threat
Antone Andrade
Security Engineer - MSSP
In the early hours one morning, the quiet rhythm of our team’s 24/7 operations was interrupted by an urgent alert. Our automated monitoring systems flagged a series of high-severity events tied to a known ransomware group. These alerts, seamlessly aggregated into Microsoft Sentinel, generated incident tickets in real-time, allowing us to jump into action immediately. For our team—working remotely across multiple shifts to provide round-the-clock protection for clients—this was just another day in the life of a Managed Security Services Provider (MSSP).
The First Signs of Trouble
The initial red flag came from a compromised shared account within the client’s environment. This account, which had additional privileges, was executing unauthorized delete actions and initiating suspicious connections to a Windows domain. Our team quickly began piecing together the details. Registry keys were being deleted, and file paths manipulated—classic signs of an attacker attempting to erase their tracks.
Using our team chat channels, the response came together seamlessly. One analyst shared a VirusTotal report that spotlighted a suspicious file: clip.dll. The file was swiftly identified as malicious, linked directly to the ransomware group. The attackers weren’t amateurs—they employed advanced techniques like scheduled tasks, Kerberoasting attempts, and targeted PowerShell commands, revealing a well-coordinated attack.
Locking it Down
Containment became the priority. We cataloged every device and account the attackers had touched, mapping their lateral movement across the client’s network. The likely entry points were internal servers and the Remote Desktop Web environment. Without delay, we disabled compromised accounts, shut down the Remote Desktop Web Server, and heightened monitoring across the client’s systems to detect any further anomalies. Additionally, we detected and removed a backdoor MFA option that the attackers had added in case the tokens were cleared.
Given the sophistication of the attack, we advised the client to engage their Forensic Incident Response Team (IRT) to lead the in-depth investigation and provide expert analysis. This collaboration allowed us to validate our containment measures, identify additional threats, and implement enhanced security protocols. Together, we worked to ensure the environment was secure and all risks were mitigated.
A Close Call with Ransomware
The forensic analysis confirmed the severity of the incident. This was a highly coordinated ransomware group, known for its precision. The good news? We stopped them before they could encrypt any data.
“By the time we’re usually involved, data encryption has already occurred, and ransom negotiations are underway. The fact that you stopped this attack in its tracks is extraordinary.”
Cleaning Up and Moving Forward
Neutralizing the immediate threat was only the beginning. Over the following weeks, we worked closely with the client and the IRT to ensure the attack was thoroughly eradicated. Logs were analyzed in granular detail, affected devices were remediated, and additional defenses were implemented to fortify the client’s environment. Every ticket—whether tied to unusual sign-ins, Kerberoast activity, or registry anomalies—was resolved with precision.
A Seamless Team Effort
This victory wasn’t achieved by any single person, but by a team that performed with absolute professionalism and precision. Across time zones and shifts, our team members handed off responsibilities seamlessly—from the overnight shift that first detected the threat to the day shift that continued the containment and cleanup efforts. Everyone played a crucial role in ensuring a smooth and effective response, demonstrating the strength of collaboration and trust in a global, remote operation.
By the end of the ordeal, every ticket was closed, the client’s systems were secure, and the team had gained valuable insights for future incidents. What could have been a devastating ransomware attack became a success story, thanks to the power of preparation, coordination, and expertise.
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