Runs a hypothesis-driven threat hunt for command-and-control activity (T1071) by querying SIEM/EDR network telemetry for anomalous outbound traffic, rare destinations, non-standard ports, and unusual connection frequencies from endpoints. Use when hunting for beaconing/C2 traffic, after threat intel flags suspicious infrastructure, or when alerts fire on anomalous connections.
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Use hunting-for-unusual-network-connections to conduct a hypothesis-driven hunt for anomalous outbound/C2 activity in [SIEM/EDR telemetry] over [time range], delivering validated findings, correlated activity, and response recommendations.
Required inputs
[SIEM/EDR telemetry]
[time range]
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SKILL.md
name: hunting-for-unusual-network-connectionsdescription: Runs a hypothesis-driven threat hunt for command-and-control activity (T1071) by querying SIEM/EDR network telemetry for anomalous outbound traffic, rare destinations, non-standard ports, and unusual connection frequencies from endpoints. Use when hunting for beaconing/C2 traffic, after threat intel flags suspicious infrastructure, or when alerts fire on anomalous connections.domain: cybersecuritysubdomain: threat-huntingtags: - threat-hunting- mitre-attack- network-analysis- c2- anomaly-detection- proactive-detectionversion: '1.0'author: mahipallicense: Apache-2.0d3fend_techniques: - File Metadata Consistency Validation- Certificate Analysis- Application Protocol Command Analysis- Content Format Conversion- File Content Analysisnist_csf: - DE.CM-01- DE.AE-02- DE.AE-07- ID.RA-05mitre_attack: - T1046- T1057- T1082- T1083- T1071
Hunting For Unusual Network Connections
When to Use
When proactively hunting for indicators of hunting for unusual network connections in the environment
After threat intelligence indicates active campaigns using these techniques
During incident response to scope compromise related to these techniques
When EDR or SIEM alerts trigger on related indicators
During periodic security assessments and purple team exercises
Prerequisites
EDR platform with process and network telemetry (CrowdStrike, MDE, SentinelOne)
SIEM with relevant log data ingested (Splunk, Elastic, Sentinel)
Sysmon deployed with comprehensive configuration
Windows Security Event Log forwarding enabled
Threat intelligence feeds for IOC correlation
Workflow
Formulate Hypothesis: Define a testable hypothesis based on threat intelligence or ATT&CK gap analysis.
Identify Data Sources: Determine which logs and telemetry are needed to validate or refute the hypothesis.
Execute Queries: Run detection queries against SIEM and EDR platforms to collect relevant events.
Analyze Results: Examine query results for anomalies, correlating across multiple data sources.
Validate Findings: Distinguish true positives from false positives through contextual analysis.
Correlate Activity: Link findings to broader attack chains and threat actor TTPs.
Document and Report: Record findings, update detection rules, and recommend response actions.
Key Concepts
Concept
Description
T1071
Application Layer Protocol
T1095
Non-Application Layer Protocol
T1571
Non-Standard Port
Tools & Systems
Tool
Purpose
CrowdStrike Falcon
EDR telemetry and threat detection
Microsoft Defender for Endpoint
Advanced hunting with KQL
Splunk Enterprise
SIEM log analysis with SPL queries
Elastic Security
Detection rules and investigation timeline
Sysmon
Detailed Windows event monitoring
Velociraptor
Endpoint artifact collection and hunting
Sigma Rules
Cross-platform detection rule format
Common Scenarios
Scenario 1: Backdoor communicating to C2 on non-standard port
Scenario 2: Data exfiltration over DNS to attacker nameserver