Endpoint Detection and Response Has Not Solved the Endpoint Security Problem
Endpoint Detection and Response platforms replaced antivirus as the dominant endpoint security technology on the basis that signature-based detection could not keep pace with the volume and variety of modern malware. The replacement was justified. EDR’s behavioral detection, continuous telemetry, and forensic capability represent a genuine improvement over signature-based antivirus in detecting and investigating endpoint threats.
The marketing that followed — the promise of comprehensive endpoint security that would significantly reduce breach frequency and impact — overstated what the technology can deliver. EDR is better than what it replaced. It is not the endpoint security solution. Endpoints continue to be compromised at scale in organizations running mature EDR deployments because the threats that matter most have adapted to operate within the behavioral envelope that EDR considers legitimate.
What EDR Detects and What It Misses
EDR excels at detecting threats that deviate significantly from normal system behavior: novel malware that makes system calls outside normal patterns, ransomware that begins mass file encryption, tools that attempt to disable security software. These are high-signal events that EDR detection logic handles well.
EDR struggles with attacks that operate within the boundaries of legitimate system behavior. Living-off-the-land techniques — attacks that use built-in Windows tools like PowerShell, WMI, and certutil rather than introducing new executables — produce behavioral signals that overlap substantially with legitimate administrative activity. An attacker who uses PowerShell to download and execute a payload is doing something that IT administrators also do. The EDR must distinguish between the legitimate administrative action and the attack, which it does imperfectly.
The imperfection manifests as alert volume. Enterprise EDR deployments generate alert volumes that security operations teams cannot fully investigate. The standard response to alert fatigue — tuning detection rules to reduce false positives — reduces the signal-to-noise ratio but also reduces detection sensitivity. The security team that tunes its EDR to eliminate false positives on legitimate PowerShell usage may be tuning out the signal from the attack that uses similar techniques.
The Coverage Problem
EDR coverage requires the EDR agent to be installed and running on every endpoint. The endpoints that do not have the agent installed are invisible to the EDR platform. In most enterprise environments, the EDR coverage is not 100 percent. Legacy systems that cannot run the agent, devices that were onboarded before the EDR requirement was established, third-party devices with network access, and cloud workloads that were not included in the initial deployment scope all represent coverage gaps.
Attackers who understand the target organization’s security stack will attempt to identify and operate through coverage gaps. A device without the EDR agent is an endpoint where behavioral detection provides no protection. The security team’s confidence in its endpoint visibility must be calibrated against its actual coverage percentage, which requires active measurement rather than assumption.
The Alert Investigation Capacity Problem
The value of EDR is realized through investigation: the alerts that are generated must be evaluated, the true positives must be escalated, and the resulting incidents must be contained. This investigation requires skilled security analysts and time. The organizations that have deployed EDR without the analyst capacity to investigate its output have purchased detection capability that they cannot fully use.
Managed Detection and Response services — where a third-party security operations team monitors and investigates EDR alerts on behalf of the organization — address the capacity problem for organizations that cannot build a 24x7 in-house SOC. The service is not equivalent to an in-house team that has organizational context and relationships. It is substantially better than an EDR deployment that generates alerts that nobody investigates overnight.
EDR is a necessary component of a mature endpoint security program. It is not a sufficient one. The organizations that treat it as sufficient have better detection capability than they had before and a security posture that is still determined primarily by whether attackers choose to apply the techniques that EDR reliably catches or the techniques that it does not.