Individual skill
hunting-for-dns-tunneling-with-zeek
Detect DNS tunneling and data exfiltration by analyzing Zeek dns.log for high-entropy subdomain queries, excessive query volume, long query lengths, and unusual DNS record types indicating covert channel communication.
internal/tools/skills/data/threat-hunting/hunting-for-dns-tunneling-with-zeek/SKILL.md
Source commit d42f381ad34843e71a42658e5c57290c713e85af
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- Yes
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- Observed behavior
- Instructions only
- Last checked
- Nov 9, 2026
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Repository context
- Repository stars (not skill ratings)
- 1,325
- Repository last updated
- Nov 9, 2026
- License
- Apache-2.0
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- cybersecurity Repository topic
- security Repository topic
- bug-bounty Repository topic
- automation Repository topic
- autonomous-pentesting Repository topic
- ai-agent Repository topic
- ai-security Repository topic
- ethical-hacking Repository topic
- golang Repository topic
- penetration-testing Repository topic
- threat-hunting Declared skill tag
- dns-tunneling Declared skill tag
- zeek Declared skill tag
- data-exfiltration Declared skill tag
- covert-channel Declared skill tag
- mitre-t1071-004 Declared skill tag
- network-monitoring Declared skill tag
- data Derived category
- security Derived category
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# Hunting for DNS Tunneling with Zeek
## When to Use
- When hunting for data exfiltration over DNS covert channels
- After threat intelligence indicates DNS-based C2 frameworks targeting your industry
- When dns.log shows unusually high query volumes to specific domains
- During investigation of suspected data theft where no HTTP/S exfiltration is found
- When monitoring for tools like iodine, dnscat2, DNSExfiltrator, or DNS-over-HTTPS tunneling
## Detection Gaps & Validation
- **Low-and-slow tunnels evade volume/length thresholds.** Padding and jitter keep queries under the 50-char length and 100/hr volume thresholds; rate-based rules miss them. Lean on per-domain unique-subdomain cardinality and qtype skew over long windows instead.
- **DoH/DoT bypasses `dns.log` entirely.** Encrypted DNS to 8.8.8.8/1.1.1.1 over 443 never appears in Zeek `dns.log` — pivot to `ssl.log` JA3 fingerprints and proxy logs for these resolvers.