EDR and XDR in plain English
A traditional antivirus scanner works like a bouncer with a list of known troublemakers: anyone on the list doesn’t get in, and anyone who isn’t on it gets through. EDR works more like video surveillance with attentive security staff. It pays attention not only to who comes in but also to what happens afterward – and steps in when someone behaves suspiciously.
EDR stands for “Endpoint Detection and Response,” meaning detection and response on endpoints. Endpoints are laptops, desktop PCs, and servers. XDR stands for “Extended Detection and Response.” “Extended” means that data from additional sources is also fed in – from the network, email, cloud services, and identity services that manage user accounts and sign-ins.
How EDR and XDR work
- Record: A small program on each endpoint, called an agent, continuously logs events: programs launched, file changes, network connections, and sign-ins.
- Detect: The solution compares these events with known attack patterns and looks for anomalous behavior. Examples: a word processor suddenly launches a command line and downloads code from the internet. Or a process tries to read passwords from memory.
- Alert: The system reports suspicious activity to the security team – with an assessment and the relevant context.
- Respond: Depending on the configuration, the solution terminates malicious processes, quarantines files, or isolates a computer from the network.
- Investigate: The stored data later shows how an attacker proceeded. This is an important foundation for digital forensics.
XDR links this data with additional sources. This makes it possible to see that, for example, a phishing email, a suspicious cloud sign-in, and an unusual process on a laptop belong to the same attack. A related technology is SIEM, which collects and analyzes logs from many systems centrally.
A practical example
Here’s a typical scenario: A construction supplier with several locations has installed an EDR solution on all of its computers. During a red teaming exercise, the testing team gains access to a workstation via a crafted email and tries to extract credentials. The EDR detects the attempt and raises an alert – on a Friday evening.
The alert lands in a mailbox that nobody reads over the weekend. Because no one responds, the testing team can try other routes undisturbed. By Monday, the team has already made its way to the accounting server; experts call this lateral movement, moving sideways through the network. The technology worked, but the process behind it didn’t. The company then reorganizes its alerting and has alerts assessed outside business hours as well.
Why does this matter for businesses?
Attackers often no longer use conspicuous malware but tools that are already present on most computers anyway, such as the operating system’s administration utilities. Traditional antivirus scanners often fail to detect such attacks. EDR focuses on behavior and can therefore also detect new attack patterns. In addition, frameworks such as NIS2 require organizations to handle security incidents – and to do that, you first have to notice them.
But EDR is not a set-and-forget solution. It only sees devices on which its agent is running. Printers, network devices, VPN gateways, or machine controllers often remain blind spots. Attackers also deliberately try to disable security software. And every alert is only as good as the response to it. That’s why many companies have their alerts assessed by a SOC, a team that continuously monitors the IT environment – either in-house or as a service.
How to protect your organization
- Roll out completely: Install the agent on all laptops, PCs, and servers. Gaps in coverage are entry points.
- Check the protection mode: Clarify whether the solution only alerts or also intervenes automatically.
- Limit exclusions: Keep exclusion lists short and review them regularly.
- Prevent tampering: Protect the agent against being uninstalled or disabled.
- Organize alerting: Define who assesses and responds to alerts – including at night and on weekends.
- Test effectiveness: Use realistic attacks to check whether detection works, for example in purple teaming, where attackers and defenders work together openly.
How Rootsektor can help
A realistic exercise shows whether your threat detection works when it counts. In Red Teaming & APT Simulation, we use the techniques of real attackers and check whether EDR, SIEM, and your team detect them and respond correctly. As a variant of or complement to red teaming, we offer purple teaming: we work through the techniques step by step together with your defenders, so detection gaps can be closed right away. If you are facing an acute security incident, our IT Emergency Response service is there to help – outside business hours via our 24/7 emergency hotline at +49 2932 465265-0.