Table of contents
The limits of detection-based security
Security analysts can only respond to incidents as quickly as Endpoint Detection and Response (EDR) and Extended Detection and Response (XDR) products identify them and generate an alert, typically after an attack has exfiltrated data or executed its malicious payload. Automated responses can quickly isolate infections, but only after a detection alert triggers its defenses.
Modern intrusions routinely subvert detection altogether by leveraging fileless malware and Living-off-the-Land (LOTL) techniques. Once deployed, malicious payloads can take seconds to profile and copy sensitive data or encrypt networks with ransomware.
Threats today require organizations to integrate security controls that prevent attacks altogether, rather than wait to detect and react to a breach.
Zero Trust controls like ThreatLocker Allowlisting and Ringfencing alongside EDR and XDR are now an operational necessity.
How EDR evolved, and where it falls short
The original strength of EDR
EDR products evolved from traditional antivirus products to combat rapidly advancing malware mechanics. Most antivirus products can only prevent known intrusions based on their file hash digests, known as virus signatures.
Antivirus products relied on regular updates to their dictionaries of static virus signatures to stay current. Newly released malware, malware that changed its file signature, and attacks designed to be completely fileless regularly outpaced and subverted antivirus. Malware began shifting from file-based executables to amorphous, adaptive code capable of moving and hiding itself among legitimate applications and processes.
Around the 2010s, increases in available computer processing power and memory enabled EDR products to close the antivirus gap by incorporating continuous monitoring capabilities into endpoint agent software.
Instead of comparing new files to a list of virus signatures, EDR agents monitored system behavior heuristically. Newly executed processes, registry modifications, and network connection events are combined with shared telemetry collected from other endpoints to correlate system events into patterns of normal user behavior.
Behavior that deviated from these patterns, such as abnormal RDP traffic or multiple failed login attempts, could be considered an indicator of compromise (IoC) and flagged for investigation or automated responses.
Rise of XDR
EDR broke ground in attack detection by enabling pattern recognition across multiple endpoints by collecting and correlating events and telemetry across agent collection points.
Attacks, however, do not start and end at the victim endpoint. Attackers must navigate entire network ecosystems, including firewalls, email exchanges, hypervisors, and cloud environments, to deploy their malware. Effective attack pattern detection now means following IoCs as they evolve across network and technology boundaries.
XDR was introduced to “extend” detection and response beyond the individual endpoint. Suspicious events are correlated across multiple technologies, not just endpoint workstations. XDR solutions can ingest data from sensors across disparate devices and networks, enabling automated responses such as blocking suspected malicious network sessions or disabling compromised user accounts.
Despite the extended scope, XDR still depends on detecting first and reacting second. It tells you when something bad happens but can’t stop it from happening in the first place. In a Zero Trust environment, detection and response remain critical; however, attack prevention enforced at the endpoint, identity, and network layers is what ultimately closes the protection gap.
Attacks that can defeat EDR and XDR
As cybercrime became increasingly profitable, attack techniques and technology advanced rapidly. EDR and XDR, despite being better poised against advanced, adaptive, and behavioral malware than antivirus, could be outmatched by stealthy innovations in malware mechanics, including the following:
LOTL attacks: Unlike antivirus software’s reliance on a static dictionary of file signatures, EDR could recognize dynamic attack patterns. Successful recognition, however, relied on identifying anomalous behavior within collected patterns of normal behavior. Attackers learned they could blend in with typical system behavior by leveraging trusted system applications, rather than writing malware as a standalone application binary.
Fileless malware: EDR primarily scans for known malicious files on a computer’s hard disk. Fileless malware often operates entirely in memory or uses existing legitimate files, so there is no "malware" file for the EDR to scan or flag.
Log tampering: EDR can correlate log files from different data and appliance sources into a storyline of how an attack was initiated and evolved. Some malware can evade detection by altering or deleting log files, leaving little forensic evidence that might enable detection.
Process injection: Malicious code can be “injected” into a running, legitimate process, so superficially, any malicious behavior appears to originate from that process. System processes are likely already included in an EDR's list of usual behavior patterns, so any malicious behavior performed by them may not appear abnormal and suspicious.
EDR blind spots: A specific list of "blind spots" where EDR visibility is limited or non-existent.
◦ Execution inside Virtual Machines (VMs).
◦ Blended processes where malicious threats hide inside legitimate memory.
◦ Injections into system binaries.
Agent tampering: Attackers may attempt to stop or uninstall an EDR product’s local endpoint software agent altogether, opening a victim host to any arbitrary abuse.
Social engineering: EDR may not detect malicious behavior if it is disguised as legitimate behavior. An attacker using stolen user credentials does not need to employ advanced techniques to conceal their behavior. They are free to pilfer sensitive data from any application or network share that the user might have access to.
Detection is not prevention
Detection of a cyber-attack requires constant endpoint monitoring to ensure suspicious behavior is observed and accurately correlated to malicious activity. That is, to detect an intrusion, it must be seen. To be seen, it must have already occurred.
EDR and XDR vendors continue to keep pace with the modern threat landscape by advancing their detection and reaction capabilities holistically against an entire network’s worth of telemetry. But they remain just that: reactions. EDR and XDR fundamentally cannot prevent attacks because they require observing the indicators of an attack already in progress.
Defense against cyberattacks is an arms race. The more advanced the attack, the more advanced the detection method must become. The more motivated the attacker, the more bespoke the attack is written against the individual victim. Detection products marketed to respond against common attack patterns cannot protect against hyper-customized attacks from motivated adversaries.
Threats now outpace response capabilities
When detection methods are not successfully subverted, EDR and XDR solutions can trigger responses to detected incidents. In large enterprises, they typically integrate with a Security Orchestration, Automation, and Response (SOAR) platform. SOAR will respond to detected malicious events and behaviors by exercising an advanced playbook of automated actions, such as disconnecting affected hosts, disabling associated user accounts, or blocking network connections. The problem becomes not one of how to respond but how to respond in time.
Modern attacks are fast, stealthy, and catastrophic. The window between compromise and damage has collapsed, often closing before a detection tool can finish processing the alert. Key statistics illustrate this urgency:
- Ransomware speed: Encryption is often completed within minutes, frequently faster than an automated playbook can isolate the host.
- Instant exfiltration: Data exfiltration often occurs in “single transactions” using legitimate tools like PowerShell, curl, or Rclone. Because these are valid system commands, the data is gone before the behavior is flagged as suspicious.
- Privilege escalation: Identity-based attacks often escalate privileges within minutes of compromise.
Isolating a host cannot stop ransomware that has already encrypted the drive. Blocked network traffic cannot retrieve data that’s already been exfiltrated.
How ThreatLocker Zero Trust products close the detection gap
Zero Trust security controls enable attack prevention by blocking any behavior that isn’t explicitly allowed. Technologies like application allowlisting and Just-in-Time (JIT) access inherently prevent malicious behavior by limiting actions and access in accordance with the principle of least privilege. ThreatLocker makes implementing Zero Trust painless by removing the overhead of granularly maintaining every permitted application and resource through its automatic, dynamic security platform modules:
Allowlisting: ThreatLocker first learns an organization’s application environment down to the individual driver and system process on every connected computer. Allowlisting policies are automatically created to permit what users typically use and deny everything else by default. Speed is no longer a factor in an attack’s success when it isn’t allowed to start.
Ringfencing: Once an application is permitted, Ringfencing may be applied to its Allowlisting policy to further prevent it from executing other applications and processes, making registry edits, reading or writing files, or initiating network sessions. Fileless malware or malware hidden within a legitimate process can’t start its payload or leverage other applications to do so on its behalf.
Elevation Control: JIT access is enforced against all users through Elevation Control. Stolen credentials cannot be pivoted into elevated privileges when Elevation Control eliminates the need for local administrators and elevates the application.
Network Control: Dynamic endpoint firewall rules can be enforced through Network Control, making lateral movement and connections to external malicious command and control servers impossible.
Storage Control: Sensitive data exfiltration becomes all but impossible with Storage Control policies dictating exactly what file paths, shares, and device interfaces are explicitly accessible to specific users, computers, and groups.
Detect: Add detection capabilities to a Zero Trust environment by deploying ThreatLocker Detect as a policy-based, responsive EDR. Detected anomalous behavior invokes automatic, arbitrary actions.
Tamper Protection: The ThreatLocker agent is protected from malicious or accidental modification through robust tamper protection.
Conclusion: Build for prevention, validate with detection
EDR and XDR remain a necessary component of a modern cybersecurity stack for their invaluable incident detection and forensics capabilities. They provide deep endpoint visibility by recording processes, memory, and network behaviors to identify and contain anomalies that slip past policy boundaries. Their insights are aggregated with telemetry from identity, cloud, email, and network sources to reveal coordinated attacks across an enterprise.
Today, organizations cannot rely solely on detection. EDR and XDR by themselves cannot keep a network secure against the adaptive threat landscape of today. Prevention must be enforced through Zero Trust controls to stop attacks before they can execute. Detection technologies must be combined with Zero Trust prevention to build a comprehensive security ecosystem. Together, the stack not only blocks untrusted actions before they can cause harm but also detects and correlates suspicious events, showing where administrators can add defenses or improve user behavior. Prevent attacks first, then fortify initial attack vectors through the visibility and forensics offered by EDR and XDR.
Ready to see how ThreatLocker delivers Zero Trust across every endpoint? Lock down application executions with Application Allowlisting, contain application abuse with Ringfencing, elevate privileges safely with Elevation Control, and implement dynamic firewall rules with Network Control. Start your 30-day free trial here.
Frequently asked questions
Are EDR and XDR still necessary if we implement Zero Trust?
Yes. EDR and XDR are valuable for detection, investigation, and forensics. Zero Trust reduces the chance an attack can execute, while EDR and XDR help validate controls and catch abnormal behavior that slips through.
What is the biggest weakness of EDR and XDR?
They typically rely on observing malicious behavior to generate an alert. That means an attacker can sometimes execute, exfiltrate data, or encrypt systems before an investigation or automated response starts.
What are common EDR and XDR blind spots?
Common blind spots include fileless techniques that run in memory, process injection into trusted binaries, activity inside virtual machines, credential-based misuse that looks like legitimate access, and attacker attempts to tamper with agents or logs.
How does allowlisting help prevent ransomware?
Allowlisting enforces default deny so unapproved executables, scripts, and payloads cannot run. Many ransomware chains fail early when the initial loader or second stage payload is blocked from executing.
How does Ringfencing help against LOTL and fileless attacks?
Ringfencing restricts what approved applications can do, such as spawning PowerShell, editing sensitive registry areas, reading protected folders, or initiating unexpected network connections. This limits abuse of legitimate tools often used in LOTL attacks.
If an attacker steals valid credentials, can EDR or XDR stop them?
Not always. Credential-based activity can look legitimate. Prevention requires least privilege, JIT access, strong access controls, segmentation, and policies that restrict what applications and identities can do even after logging in.
Why is speed such a problem in modern attacks?
Many intrusions move quickly. Exfiltration can happen in a short window using legitimate tools, and ransomware can encrypt systems fast. If response begins only after detection, the damage may already be done.
What does a practical stack look like: Zero Trust plus detection?
Use Zero Trust controls to prevent execution and limit lateral movement, then use detection to validate, investigate, and improve. A strong stack combines default deny, containment, JIT access, network restrictions, storage controls, and monitored alerting.
