What Is Cobalt Strike and Why Attackers Use It in Cyber Attacks
Neil Hare-Brown- 2 days ago
- 3 min read
You’ve stopped the phishing email, or blocked the fake software download — but the real attack may only just be starting.
Once inside a system, many cybercriminals don’t launch ransomware immediately. Instead, they deploy advanced tools to explore, escalate, and prepare for maximum impact.
One of the most common tools they use? Cobalt Strike.
In this blog, we explain what Cobalt Strike is, how attackers abuse it, and what defenders can do to detect and respond before serious damage is done.
What Is Cobalt Strike?
Cobalt Strike is a legitimate red teaming tool — originally designed for penetration testers to simulate real-world threats.
It includes capabilities such as:
Deploying “beacons” on compromised machines to maintain access
Executing commands remotely without alerting the user
Logging keystrokes or capturing screenshots
Moving laterally across networks
Delivering second-stage payloads such as ransomware
While its original purpose is ethical testing, pirated versions of Cobalt Strike are widely used by threat actors — especially ransomware groups.
Why Do Cybercriminals Use It?
Cobalt Strike is highly appealing to attackers for several reasons:
✅ It blends in – Designed to avoid detection, it mimics legitimate traffic and behaviours.
✅ It’s modular – Attackers can customise payloads, persistence methods, and communication protocols.
✅ It enables full control – Once a beacon is in place, attackers can explore the network in stealth.
✅ It’s battle-tested – It’s proven to work in real-world environments and is supported by a vast library of community tools.
How Cobalt Strike Is Used in Real Attacks
Cobalt Strike is rarely the first stage — it’s used after initial access, often gained via:
Phishing emails with attachments or links
Fake software updates or drive-by downloads
Malvertising or SEO poisoning
Exploitation of public-facing systems
Once the attacker has access, they deploy a Cobalt Strike beacon, which allows:
Persistence – Maintain access across reboots
Lateral movement – Discover and exploit other systems inside the network
Credential theft – Dump hashes, steal cookies or session tokens
Staging – Download ransomware or exfiltrate sensitive data
Many ransomware operations rely on Cobalt Strike during the preparation phase — before encryption begins.
Recent Campaigns Involving Cobalt Strike
Conti and LockBit
Both groups have used Cobalt Strike extensively to map networks and identify high-value targets before launching attacks.
IcedID Loader Chains
In many cases, malware loaders like IcedID deliver Cobalt Strike as the next stage after initial compromise.
SocGholish Campaigns
Fake browser updates may lead to Cobalt Strike payloads once the victim’s device is under attacker control.
How to Detect and Defend Against Cobalt Strike
Detecting Cobalt Strike can be challenging — especially since it’s designed to evade standard antivirus tools.
However, there are signs defenders can look for:
Key Defences:
Endpoint Detection and Response (EDR) Modern EDR tools can identify beacon-like behaviours such as periodic callbacks, Powershell misuse, or fileless execution.
Network Monitoring Look for unusual outbound traffic patterns, connections to known command-and-control (C2) servers, or encrypted traffic to suspicious IPs.
Disable Unused Tools If your organisation doesn’t use Cobalt Strike legitimately, block related binaries and behaviours through application whitelisting.
Review PowerShell and WMI Logs Cobalt Strike frequently uses these tools for stealthy commands. Monitoring them can help flag early activity.
Run threat hunting exercises Regularly review your environment for signs of beaconing or post-exploitation activity.
What to Do If Cobalt Strike Is Detected?
✅ Isolate the host immediately
It may be one of several infected systems.
✅ Check for lateral movement
Cobalt Strike is rarely used in isolation.
✅ Investigate recent downloads and logs
Look for phishing or malware used in the initial compromise.
✅ Engage incident response experts
Storm Guidance’s team can support containment and investigation.
✅ Review credentials and privilege usage
Attackers may have harvested account access for future use.
How STORM Guidance Can Help
✔ Cobalt Strike incident investigation
Our team analyses your environment to determine how the tool was deployed and whether other systems are compromised.
✔ Malware and ransomware containment
We work quickly to identify lateral movement and stop further spread before ransomware is launched.
✔ EDR and logging strategy reviews
We help you improve visibility, monitor for beacon-like behaviours, and identify gaps in endpoint protection.
✔ Threat actor engagement
If attackers have demanded payment or stolen data, we handle ransomware negotiation and extortion response.
✔ Resilience through proactive exercises
We help run cyber incident exercises that simulate post-exploitation tools like Cobalt Strike.
Final Thoughts
Cobalt Strike may have started as a tool for defenders — but today, it’s also a weapon in the hands of attackers.
By recognising the signs of post-exploitation tools and investing in behavioural detection, your business can stop ransomware attacks before encryption ever begins.
To improve your threat visibility and prepare for the tactics used in real-world breaches, speak to Storm Guidance about your incident response and cyber resilience strategy.
