analyzing-dns-logs-for-exfiltration

analyzing-dns-logs-for-exfiltration is a skill for Claude Code from Mikaru0Mystic/sectinel. It costs 73 tokens per session (3,103 once invoked), scanned A, a copy of analyzing-dns-logs-for-exfiltration, Apache-2.0.

A security procedure for examining DNS query logs, which record requests to translate domain names into network addresses. It looks for data theft, malware control traffic, and algorithmically generated domains hidden in DNS activity.

In plain words
What is it for?
Use it to analyze DNS logs in a SIEM, measure unusual query volume or randomness, inspect long subdomains and TXT requests, and investigate DNS-based command-and-control traffic.
Why use it?
It helps detect covert communication that may bypass ordinary network defenses, including DNS tunneling that encodes stolen data in domain requests.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the cybersecurity-skills plugin — 56 skills shipped together

Good fit Use it to analyze DNS logs in a SIEM, measure unusual query volume or randomness, inspect long subdomains and TXT requests, and investigate DNS-based command-and-control traffic.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/mikaru0mystic/sectinel/analyzing-dns-logs-for-exfiltration
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add Mikaru0Mystic/sectinel --skill analyzing-dns-logs-for-exfiltration
Clone the repo
git clone --depth 1 https://github.com/Mikaru0Mystic/sectinel

Made for: Claude Code.

Or install cybersecurity-skills, the plugin that ships this one along with the rest of its 56 skills.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for analyzing-dns-logs-for-exfiltration

README.md
[![agentmods](https://agentmods.dev/badge/skills/mikaru0mystic/sectinel/analyzing-dns-logs-for-exfiltration/github.svg)](https://agentmods.dev/skills/mikaru0mystic/sectinel/analyzing-dns-logs-for-exfiltration)
Your own site
<a href="https://agentmods.dev/skills/mikaru0mystic/sectinel/analyzing-dns-logs-for-exfiltration"><img src="https://agentmods.dev/badge/skills/mikaru0mystic/sectinel/analyzing-dns-logs-for-exfiltration/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for analyzing-dns-logs-for-exfiltration

Your own site · 80×15
<a href="https://agentmods.dev/skills/mikaru0mystic/sectinel/analyzing-dns-logs-for-exfiltration"><img src="https://agentmods.dev/badge/skills/mikaru0mystic/sectinel/analyzing-dns-logs-for-exfiltration.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 73 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,103 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 98% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00073 $0.03103
Opus 5 $0.00036 $0.01551
Sonnet 5 $0.00015 $0.00621
Haiku 4.5 $0.00007 $0.00310

Measured 11d ago against content hash fc62657d797a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

analyzing-dns-logs-for-exfiltration scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 11d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/agent.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

98% identical to analyzing-dns-logs-for-exfiltration — 11 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

arsenal/Anthropic-Cybersecurity-Skills/skills/analyzing-dns-logs-for-exfiltration/SKILL.md · 305 lines

How it starts

The opening of the file, as written. The whole thing — 305 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Analyzing DNS Logs for Exfiltration

When to Use

Use this skill when:

  • SOC teams suspect data exfiltration through DNS tunneling to bypass firewall/proxy controls
  • Threat intelligence indicates adversaries using DNS-based C2 channels (e.g., Cobalt Strike DNS beacon)
  • UEBA detects anomalous DNS query volumes from specific hosts
  • Malware analysis reveals DNS-over-HTTPS (DoH) or DNS tunneling capabilities

Do not use for standard DNS troubleshooting or availability monitoring — this skill focuses on security-relevant DNS abuse detection.

Prerequisites

  • DNS query logging enabled (Windows DNS Server, Bind, Infoblox, or Cisco Umbrella)
  • DNS logs ingested into SIEM (Splunk with Stream:DNS, dns sourcetype, or Zeek DNS logs)
  • Passive DNS data for historical domain resolution analysis
  • Baseline of normal DNS behavior (query volume, domain distribution, TXT record frequency)
  • Python with math and collections libraries for entropy calculation

Workflow

Step 1: Detect DNS Tunneling via Subdomain Length Analysis

DNS tunneling encodes data in subdomain labels, creating unusually long queries:

index=dns sourcetype="stream:dns" query_type IN ("A", "AAAA", "TXT", "CNAME", "MX")
| eval domain_parts = split(query, ".")
| eval subdomain = mvindex(domain_parts, 0, mvcount(domain_parts)-3)
| eval subdomain_str = mvjoin(subdomain, ".")
| eval subdomain_len = len(subdomain_str)
| eval tld = mvindex(domain_parts, -1)
| eval registered_domain = mvindex(domain_parts, -2).".".tld
| where subdomain_len > 50
| stats count AS queries, dc(query) AS unique_queries,
        avg(subdomain_len) AS avg_subdomain_len,
        max(subdomain_len) AS max_subdomain_len,
        values(src_ip) AS sources
  by registered_domain
| where queries > 20
| sort - avg_subdomain_len
| table registered_domain, queries, unique_queries, avg_subdomain_len, max_subdomain_len, sources

Step 2: Detect High-Entropy Domain Queries (DGA Detection)

Domain Generation Algorithms produce random-looking domains:

Read the full file on GitHub · 305 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 11d ago First seen · 305 lines · 73 tokens per session scan A fc62657d797a

Subscribe to this mod's changes

analyzing-dns-logs-for-exfiltration is a skill published in the GitHub repository Mikaru0Mystic/sectinel (11 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 73 tokens to every session and 3,103 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. It is 98% identical to analyzing-dns-logs-for-exfiltration, differing in 11 lines, and is treated as a copy.

Related

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