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ClaudSkills / Security / threat-hunting

Detect C2 Beaconing

Category: Security  ·  Sub-category: threat-hunting  ·  Last updated:
Detection and hunt methodology for command-and-control beaconing, where an implant calls home on a regular interval over HTTP(S), DNS, or a tunnel service, hidden inside normal egress (MITRE ATT&CK T1071 Application Layer Protocol, T1071.004 DNS, T1573 Encrypted Channel, T1571 Non-Standard Port, T1572 Protocol Tunneling, T1090 Proxy; tactic TA0011 Command and Control). Works from Zeek conn.log/ssl.log/dns.log, Suricata EVE JSON, firewall and web-proxy logs, NetFlow/IPFIX, and endpoint Sysmon Event ID 3/22. It gives the defender's view of beacon periodicity and jitter, JA3/JA3S and JA4 TLS fingerprinting, and tunnel-service detection, plus hunt steps and hardening. Use when hunting for regular callbacks, triaging a long-lived outbound connection, analyzing JA3/JA4 hashes, investigating suspected Cobalt Strike, Sliver, or Mythic C2, chasing DNS or HTTPS tunneling, or baselining egress for periodic traffic.
Security AStatic scan found no risk patternsHow grading works ›

What this skill does

Detect C2 Beaconing is a community-contributed Claude Code skill in the threat-hunting sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/detect-c2-beaconing/ and loads when your prompt matches the skill's trigger.

When to invoke it: Use when hunting for regular callbacks, triaging a long-lived outbound connection, analyzing JA3/JA4 hashes, investigating suspected Cobalt Strike, Sliver, or Mythic C2, chasing DNS or HTTPS tunneling, or baselining egress for periodic traffic.

Who uses this skill

The Detect C2 Beaconing Claude Code skill is built for security engineers, penetration testers, DevSecOps practitioners, and development teams hardening codebases and infrastructure. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 211,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).

How to install

Free

Manual install (2 steps)

mkdir -p ~/.claude/skills/detect-c2-beaconing
curl -L https://claudskills.com/skills/detect-c2-beaconing/SKILL.md \
  -o ~/.claude/skills/detect-c2-beaconing/SKILL.md

Or just download SKILL.md directly and drop it into ~/.claude/skills/detect-c2-beaconing/. Claude Code auto-discovers it on next session.

Skills live at ~/.claude/skills/detect-c2-beaconing/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\detect-c2-beaconing\SKILL.md on Windows. See the full install guide for step-by-step instructions.

Telegram

📱 Install from your phone or desktop Telegram

Open @claudskills_bot on Telegram, tap Open Desktop App, and the desktop app installs this skill for you. Or share the bot link with a colleague — they get the same one-tap install. Learn more →

Pro

One-click install via the desktop app

The ClaudSkills desktop app installs any skill directly into ~/.claude/skills/ with one click — no terminal required. Pro starts at $9/mo or $149 lifetime.

Pro

For the full experience including quality scoring and one-click install features for each skill — upgrade to Pro.

See pricing → Download desktop app

Frequently asked questions

How do I install the Detect C2 Beaconing Claude Code skill?
Install via the ClaudSkills desktop app (one click) or copy SKILL.md from the source repository to ~/.claude/skills/detect-c2-beaconing/SKILL.md and restart Claude Code. Both flows are detailed at claudskills.com/install/.
What does the Detect C2 Beaconing skill do?
Detection and hunt methodology for command-and-control beaconing, where an implant calls home on a regular interval over HTTP(S), DNS, or a tunnel service, hidden inside normal egress (MITRE ATT&CK T1071 Application Layer Protocol, T1071.004 DNS, T1573 Encrypted Channel, T1571 Non-Standard Port, T1572 Protocol Tunneling, T1090 Proxy; tactic TA0011 Command and Control). Works from Zeek conn.log/ssl.log/dns.log, Suricata EVE JSON, firewall and web-proxy logs, NetFlow/IPFIX, and endpoint Sysmon Event ID 3/22. It gives the defender's view of beacon periodicity and jitter, JA3/JA3S and JA4 TLS fingerprinting, and tunnel-service detection, plus hunt steps and hardening. Use when hunting for regular callbacks, triaging a long-lived outbound connection, analyzing JA3/JA4 hashes, investigating suspected Cobalt Strike, Sliver, or Mythic C2, chasing DNS or HTTPS tunneling, or baselining egress for periodic traffic.
Is this skill free to install?
Yes. ClaudSkills is an open registry — every skill keeps its source repository's license, and manual install via copy is free. ClaudSkills Pro ($9/mo, $79/yr, or $149 one-time) adds one-click install via the desktop app and a multi-signal Quality Score.
When should I use the Detect C2 Beaconing skill?
Use Detect C2 Beaconing when your Claude Code task falls under the Security category — specifically in the threat hunting area. Claude Code auto-discovers installed skills and invokes the right one based on the task description, so you can also ask Claude directly (e.g. "use Detect C2 Beaconing" or describe the task and let Claude pick). Browse related skills at /category/security/.
What is a Claude Code skill and how does the Detect C2 Beaconing skill fit in?
A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. Detect C2 Beaconing is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Security category. Learn more at /learn/what-is-a-claude-skill/.

Attribution & license

Cite this skill

If you reference this skill in a blog post, paper, or documentation, you can cite it as:

APA
umbrasec-labs. (2026). Detect C2 Beaconing [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/detect-c2-beaconing/
BibTeX
@misc{detect-c2-beaconing-2026,
  author    = {umbrasec-labs},
  title     = {Detect C2 Beaconing [Claude Code skill]},
  year      = {2026},
  publisher = {ClaudSkills},
  url       = {https://claudskills.com/skills/detect-c2-beaconing/}
}

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Security scan

Grade A · scanned 2026-10-25 — free static scan against the OWASP Agentic Skills Top 10.

No risk patterns were found in any of the ten OWASP-aligned categories. How grading works ›

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More Security skills

Browse all Security skills in the ClaudSkills registry, or explore these other picks from the same category:

Browse all Security skills → Top 100 skills
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