EDR: Detection After the Breach
Endpoint Detection and Response (EDR) emerged in the mid-2010s as a response to the limitations of traditional antivirus. Where AV relied on signature matching — comparing files against a database of known threats — EDR continuously monitors endpoint behaviour and detects anomalies that suggest compromise. CrowdStrike, SentinelOne, Microsoft Defender for Endpoint, and Coro all operate in this space. EDR records process executions, file modifications, registry changes, and network connections on every protected endpoint. When behaviour matches known attack patterns (MITRE ATT&CK techniques) or deviates significantly from baseline, EDR generates alerts and can automatically isolate the endpoint. Gartner estimates that by 2025, 60% of enterprises will have replaced legacy AV with EDR — up from 30% in 2022.
XDR: Connecting the Dots
Extended Detection and Response (XDR) extends the EDR concept beyond the endpoint to correlate telemetry across email, network, cloud workloads, and identity systems. Where EDR might see a suspicious process on a single laptop, XDR can correlate that event with a phishing email received 30 minutes earlier, a new Azure AD sign-in from an unusual location, and lateral movement attempts across the network. This cross-domain visibility dramatically reduces mean time to detect (MTTD) and mean time to respond (MTTR). Palo Alto Networks' Unit 42 found that XDR reduced MTTD from an average of 197 days to under 24 hours in organisations that deployed it across all telemetry sources. The key differentiator is integration: true XDR platforms ingest and correlate data natively, rather than simply aggregating alerts from separate tools.
The Exfiltration Gap
Here is what EDR and XDR do not do: they do not prevent data from leaving your network. This is not a criticism — it is simply not what they were designed for. EDR detects threats and responds to malicious behaviour on the endpoint. XDR correlates those detections across your environment. Both are reactive by nature: they respond to detected anomalies. Data exfiltration, however, often occurs through channels that look entirely normal — HTTPS connections to cloud services, DNS queries, encrypted tunnels that mimic legitimate traffic. An attacker using living-off-the-land techniques (PowerShell, WMI, legitimate cloud storage APIs) can exfiltrate gigabytes of data without triggering EDR alerts. IBM's 2024 breach report found that the average time to identify a breach involving stolen credentials was 292 days — during which time exfiltration proceeds undetected.
- EDR detects threats, does not monitor outbound data flows
- XDR correlates detections, does not classify outbound traffic
- Living-off-the-land techniques bypass behavioural detection
- Exfiltration over HTTPS and DNS often indistinguishable from normal traffic
- Average 292 days to identify credential-based breaches (IBM 2024)
Closing the Gap: EDR + ADX
The answer is not to choose between EDR and anti data exfiltration — it is to deploy both. EDR handles detection and response for threats on the endpoint. ADX handles prevention of data leaving the network through any unauthorised channel. Together, they create a defence that addresses both sides of the attack lifecycle: the intrusion and the objective. In our managed security stacks, we deploy Coro for endpoint detection and response alongside BlackFog for anti data exfiltration. This combination means that even when Coro detects a threat and begins response, BlackFog has already ensured that no data left the device during the window between compromise and detection. For the average 292-day detection window, that is 292 days of data theft prevented.