The Seven-Minute Ransomware Containment: How Agentic AI Stopped an Attack Before It Spread

When ransomware hits, every second counts. Encryption can begin within minutes, lateral movement can unfold just as fast, and by the time a human analyst receives an alert, damage may already be underway.

But in a recent real-world incident inside one of our customer environments, Ontinue’s Cyber Defenders, armed with agentic AI, turned what could have become a widespread ransomware event into a seven-minute containment success. This is the story of how it happened, and why the future of ransomware defense will depend on agentic AI-driven speed.

A Sudden Alert on an Internet-Facing Server

It started with a Microsoft Defender for Endpoint (MDE) alert: a suspicious file had appeared on a Tier 2, internet-facing server, the kind of system attackers love to target because of its exposure and access pathways. Historically, an alert like this would trigger a multi-step, time-consuming workflow:

• Identify the host
• Validate the file
• Check execution history
• Review user activity
• Pivot into identity logs
• Correlate other endpoint alerts
• Assess lateral movement risk

Under pressure, even highly skilled defenders can lose critical minutes gathering these puzzle pieces.

But not this time.

Agentic AI Agent Triggered Before the Analyst Even Opened the Ticket

The moment the alert appeared, Ontinue’s Autonomous Investigator agent, powered by agentic AI began analyzing the event in the background. Before a human even touched the ticket, the AI agent autonomously performed the early investigative work that defenders would normally spend 15–20 minutes collecting:

It summarized:

• The server type and OS
• The file name and hash
• Related process activity
• Whether this file or behavior had appeared before anywhere in the environment
• Whether other alerts had recently fired on the same asset
• Identity context—including the account used during the suspicious activity

Then the most critical detail surfaced:

The file had been dropped via RDP using a compromised local admin account.

That single insight immediately escalated the severity. A local admin delivering a ransomware-patterned file on an internet-facing system is a classic high-impact precursor to full encryption.

Since the AI agent brought this context directly to the defender – as a ready-to-read summary – they didn’t lose precious time pivoting between tools or building hypotheses.

Minute 1–3: Analysts Validate the Threat

With the AI agent’s high-fidelity summary already in hand, the Cyber Defender was able to immediately confirm:

• The ransomware file matched a known family
• Recent RDP login activity aligned with attacker behavior
• The local admin account activity was anomalous
• No other lateral movement was yet observed

They didn’t need to run Sentinel queries or manually assemble a timeline. The AI had already surfaced it.

Minute 4–7: Containment and Customer Notification

Armed with a precise understanding of the threat, the SOC:

From initial alert to full containment: seven minutes.

To put that into perspective:

Typical ransomware families can begin encrypting files in as little as 15 minutes. In many organizations, it takes longer than that just to gather the context required to begin effective investigation.

Here, the use of an agentic AI agent cut out 70% of the early investigative work, shrinking a potential 30-minute triage to a lightweight, AI-driven process that put defenders immediately in control.

Why AI Speed Matters: Ransomware Doesn’t Wait

Too often, organizations underestimate the speed at which ransomware unfolds. The attacker’s playbook is predictable:

1. Gain initial access
2. Move quickly
3. Deploy payload
4. Encrypt
5. Exfiltrate
6. Demand payment

Every phase is measured in minutes, not hours.

This incident shows what’s possible when an agentic AI agent reduces the cognitive and operational load on defenders. Instead of combing through logs, pivoting between tools, or writing queries, analysts can immediately focus on decision-making, not data gathering.

Agentic AI Changes the Timeline and the Outcome

In this incident, the Agentic AI agent:

• Interpreted signals from multiple Microsoft Security tools
• Built a unified summary
• Highlighted anomalies and probable root cause
• Surfaced insights defenders needed to make immediate calls
• Removed the investigative drag that slows down most SOC teams

The result wasn’t just speed, it was prevention.

Ransomware never got the opportunity to execute its full kill chain.

This Is What “Nonstop SecOps” Looks Like

This seven-minute shutdown isn’t an outlier, it’s the new standard for organizations leveraging AI-driven MXDR. As attackers automate, accelerate, and innovate, defenders need more than incremental improvements. They need:

• Instant context
• Autonomous investigation
• Rapid decision support
• Integrated identity and endpoint insights
• Actionable summaries—not raw data

Ransomware isn’t slowing down. But with agentic AI, neither are we.

If you’d like help understanding how an agentic AI agent can accelerate your security operations or reduce your incident response timelines, talk to your cyber advisor. Ontinue is here to help you stay ahead of threats, no matter how fast they move.