seikaikyo/hunting-for-data-exfiltration-indicators
external/anthropic-cybersecurity-skills/skills/hunting-for-data-exfiltration-indicators/SKILL.md
Hunt for data exfiltration by analyzing Zeek and Suricata network telemetry for unusual data flows, DNS tunneling via large/frequent TXT queries, uploads to personal cloud storage, and encrypted-channel abuse, correlated against threat intel on destination domains. Use when hunting for data theft in a compromised environment, investigating unusual outbound data volumes, or determining what data was stolen during incident response.
$ install --global
skillsauthnpx skillsauth add seikaikyo/dash-skills hunting-for-data-exfiltration-indicatorsInstall this skill globally with one command. Works with Claude Code, Cursor, and Windsurf.
Security Scan Results
3 of 9 scanners reported clean
Some scanners were skipped, did not run, or reported a non-clean status. Review each row below.
3
Scanners Passed
9
Scanners in report
Clean
TrivyContainer and dependency vulnerability scanner
95%
Clean
SemgrepStatic code analysis for vulnerabilities
95%
Clean
mcp-scan (Snyk)Model Context Protocol security validation
95%
Skipped
Snyk (dep)Open source security scanning
50%
Skipped
Socket.devSupply chain security analysis
50%
Skipped
VirusTotalMulti-engine malware detection
50%
Skipped
CrowdStrikeAdvanced threat intelligence
50%
Skipped
OSV-ScannerOpen Source Vulnerability database check
50%
Skipped
OWASP Dep-Check
50%
Last scanned: Aug 14, 2026, 3:56 AM335.8s7 files scanned
SKILL.md
- name:
- hunting-for-data-exfiltration-indicators
- description:
- Hunt for data exfiltration by analyzing Zeek and Suricata network telemetry for unusual data flows, DNS tunneling via large/frequent TXT queries, uploads to personal cloud storage, and encrypted-channel abuse, correlated against threat intel on destination domains. Use when hunting for data theft in a compromised environment, investigating unusual outbound data volumes, or determining what data was stolen during incident response.
- domain:
- cybersecurity
- subdomain:
- threat-hunting
- version:
- 1.0
- author:
- mahipal
- license:
- Apache-2.0
Hunting for Data Exfiltration Indicators
When to Use
- When hunting for data theft in compromised environments
- After detecting unusual outbound data volumes or patterns
- When investigating potential insider threat data theft
- During incident response to determine what data was stolen
- When threat intel indicates data exfiltration campaigns targeting your sector
Prerequisites
- Network proxy/firewall logs with byte-level data transfer metrics
- DLP solution or CASB with cloud upload visibility
- DNS query logs for DNS exfiltration detection
- Email gateway logs for attachment monitoring
- SIEM with data volume anomaly detection capabilities
Workflow
- Define Exfiltration Channels: Identify potential channels (HTTP/S uploads, DNS tunneling, email attachments, cloud storage, removable media, encrypted protocols).
- Baseline Normal Data Flows: Establish baseline outbound data transfer volumes per user, host, and destination over a 30-day window.
- Detect Volume Anomalies: Identify hosts or users transferring significantly more data than baseline to external destinations.
- Analyze Transfer Destinations: Check destination domains/IPs against threat intel, identify newly registered domains, personal cloud storage, and foreign infrastructure.
- Inspect Protocol Abuse: Look for DNS tunneling (large/frequent TXT queries), ICMP tunneling, or data hidden in allowed protocols.
- Correlate with File Access: Link exfiltration indicators to file access events on sensitive file shares, databases, or repositories.
- Report and Contain: Document findings with evidence, estimate data exposure, and recommend containment actions.
Key Concepts
| Concept | Description | |---------|-------------| | T1041 | Exfiltration Over C2 Channel | | T1048 | Exfiltration Over Alternative Protocol | | T1048.001 | Exfiltration Over Symmetric Encrypted Non-C2 | | T1048.002 | Exfiltration Over Asymmetric Encrypted Non-C2 | | T1048.003 | Exfiltration Over Unencrypted/Obfuscated Non-C2 | | T1567 | Exfiltration Over Web Service | | T1567.002 | Exfiltration to Cloud Storage | | T1052 | Exfiltration Over Physical Medium | | T1029 | Scheduled Transfer | | T1030 | Data Transfer Size Limits (staging) | | T1537 | Transfer Data to Cloud Account | | T1020 | Automated Exfiltration |
Tools & Systems
| Tool | Purpose | |------|---------| | Splunk | SIEM for data volume analysis and SPL queries | | Zeek | Network metadata for data flow analysis | | Microsoft Defender for Cloud Apps | CASB for cloud exfiltration | | Netskope | Cloud DLP and exfiltration detection | | Suricata | Network IDS for protocol anomaly detection | | RITA | DNS exfiltration and beacon detection | | ExtraHop | Network traffic analysis for data flow |
Common Scenarios
- Cloud Storage Exfiltration: User uploads sensitive documents to personal Google Drive or Dropbox via browser.
- DNS Tunneling: Malware exfiltrates data encoded in DNS subdomain queries to attacker-controlled nameserver.
- HTTPS Upload: Compromised system POSTs large data blobs to C2 server over encrypted HTTPS.
- Email Attachment Exfiltration: Insider forwards sensitive documents to personal email accounts.
- Staging and Compression: Adversary stages data in compressed archives before slow exfiltration to avoid detection.
Output Format
Hunt ID: TH-EXFIL-[DATE]-[SEQ]
Exfiltration Channel: [HTTP/DNS/Email/Cloud/USB]
Source: [Host/User]
Destination: [Domain/IP/Service]
Data Volume: [Bytes/MB/GB]
Time Period: [Start - End]
Protocol: [HTTPS/DNS/SMTP/SMB]
Files Involved: [Count/Types]
Risk Level: [Critical/High/Medium/Low]
Confidence: [High/Medium/Low]
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