What Are the XDR Security Layers?

Extended detection and response (XDR) uses a broader range of data sources to enable detection, investigation, and response across multiple security layers. XDR breaks down security silos to identify and reveal a complete attack story in a single view.

XDR: telling a complete story

When it comes to threat detection, the job of the security operations centre (SOC) analyst is to connect the dots from initial infiltration, through lateral movement, to any exfiltration. This process allows for a quicker understanding of the impact and the response actions needed.

The more data sources and security vectors you bring into a single, integrated XDR platform, the greater the correlation opportunities, and the more comprehensive the investigation and response.

For example, today an analyst might use an endpoint detection and response (EDR) tool to get detailed visibility into suspicious activity on managed endpoints – but then have a separate siloed view of network security alerts and traffic analysis. As for the cloud workloads, the analyst likely has limited visibility to identify suspicious activity.

All parts of the environment generate noisy alerts that are likely sent to a security information and event management (SIEM). The analyst can see the alerts, but misses out on a detailed record of all the activity between alerts. Without additional correlation, the analyst will miss important attack details left buried in alerts without context or a way to connect related events. 

XDR brings the layers together so security analysts can see the bigger picture and quickly explain what may be happening in the enterprise, including how the user got infected, what the first point of entry was, and what or who else is part of the same attack.

Endpoint

Efficient endpoint activity recording is necessary to analyse how a threat might have arrived, changed, and spread across endpoints. Using XDR, you can sweep for indicators of compromise (IoCs) and hunt for threats based on indicators of attack (IOAs).

Detect: Search for and identify suspicious and dangerous endpoint events

Investigate: What happened on the endpoint? Where did the event come from? How did it propagate across other endpoints?

Respond: Isolate the event, stop processes, delete/restore files

Many organisations may start with endpoint, via EDR tools. While EDR is a good first step, it can miss the beginning and/or end of the attack story. What occurred before it landed on the endpoint? Did it come in through email, and did others receive that same email? What happened after it landed on an endpoint? Was there lateral movement to a server or container? Did it spread to an unmanaged device?

Email

Given that 94% of breaches begin through email,[1]  the ability to identify compromised accounts and detect malicious email threats is a critical piece of an organisation’s broader threat detection capability.

Detect: Search for and identify email threats, compromised accounts, highly attacked users, and email attack patterns

Investigate: Who enacted the infiltration? Who else received the malicious email?

Respond:  Quarantine email, block email senders, reset accounts

Email, as the number one attack vector, should be a priority expansion point for cross-layered detection and response. Email threats often don’t impact endpoints until a user clicks on an attachment or a link embedded in the email. An undetonated threat could be sitting in multiple inboxes undetected. Connecting an endpoint detection with the originating email means you can automatically search inboxes to find who else received the malicious email and if the malicious attachment or URL is also in other users’ mailboxes. You can then subsequently quarantine the emails and remove the threat to prevent any additional spread and damage.

Network

Network analytics is a great way to find targeted attacks as they spread laterally or communicate with command and control (C&C) servers. Network analytics can help filter the events from the noise and reduce blind spots, such as the internet of things (IoT) and unmanaged devices.

Detect: Search for and identify anomalous behavior as threats spread

Investigate: How does a threat communicate? How does it move across the organisation? 

Respond: Outline the scope of the attack

Network logs provide a comprehensive source of data to help you understand the scope of an attack, but without correlating those logs with other security alerts, it’s hard to get the context you need to assess what’s related and important. For this reason, network and endpoint create a powerful combination. By correlating the data, something that might have seemed benign at just the endpoint layer, such as suspicious PowerShell activity, becomes a high priority alert when it is considered alongside associated C&C communication with a server.

Servers and cloud workloads

Much like endpoints, this involves efficient activity recording to analyse how a threat might have arrived and spread across servers and cloud workloads. You can sweep for IoCs and hunt based on IoAs.

Detect: Search for and identify threats specifically targeting servers, cloud workloads, and containers

Investigate: What happened within the workload? How did it propagate? 

Respond: Isolate server, stop processes

Organisations may employ EDR tools for servers and cloud workloads, but may sacrifice effectiveness in doing so. EDR alone is not equipped to address new cloud models nor provide the needed type of data and visibility. As with any vector, correlating information from server environments can validate suspicious activity as malicious – such as servers that communicate with an IP address in a country they’ve never communicated with before – by linking it with activity data from other layers, be it endpoint and/or network.

XDR Security Topics

[1] Verizon 2019 Data Breach Investigations Report