Files
Anthropic-Cybersecurity-Skills/skills/hunting-for-dns-based-persistence/SKILL.md
T
Mahipal 2fb6a9faff Rewrite 548 skill descriptions to the activation rubric
Each rewritten description now states both what the skill does (concrete
capability, named tools/artifacts) and an explicit when-to-use trigger,
improving agent discovery/activation. Grounded in each skill's own body;
changes confined to the `description` field only (bodies and all other
frontmatter untouched). Produced by a gated audit->rewrite->recheck loop
(548 -> 0 flagged) with a sampled anti-invention check (0 ungrounded).

Schema: 817/817 pass. Framework-ID gate: 0 defects.
2026-08-02 09:32:13 -07:00

3.1 KiB

name, description, domain, subdomain, tags, version, author, license, nist_csf, mitre_attack
name description domain subdomain tags version author license nist_csf mitre_attack
hunting-for-dns-based-persistence Hunts for DNS-based persistence mechanisms such as DNS hijacking, dangling CNAME records enabling subdomain takeover, wildcard DNS abuse, and unauthorized zone or NS delegation changes, using passive DNS history (SecurityTrails API), Route53/Azure DNS/Cloudflare audit logs, and zone transfer analysis. Use when investigating suspected DNS hijacking or subdomain takeover, or when threat hunting for DNS record tampering that persists across credential rotations and endpoint reimaging. cybersecurity threat-hunting
dns
persistence
threat-hunting
passive-dns
dns-hijacking
subdomain-takeover
securitytrails
1.0 mahipal Apache-2.0
DE.CM-01
DE.AE-02
DE.AE-07
ID.RA-05
T1046
T1057
T1082
T1083
T1547

Hunting for DNS-based Persistence

Overview

Attackers establish DNS-based persistence by hijacking DNS records, creating unauthorized subdomains, abusing wildcard DNS entries, or modifying NS delegations to redirect traffic through attacker-controlled infrastructure. These techniques survive credential rotations, endpoint reimaging, and traditional remediation because DNS changes persist independently of compromised hosts. Detection requires passive DNS historical analysis, zone file auditing, and monitoring for unauthorized record modifications. This skill covers hunting methodologies using SecurityTrails passive DNS API, DNS audit logs from Route53/Azure DNS/Cloudflare, and zone transfer analysis.

When to Use

  • When investigating security incidents that require hunting for dns based persistence
  • When building detection rules or threat hunting queries for this domain
  • When SOC analysts need structured procedures for this analysis type
  • When validating security monitoring coverage for related attack techniques

Prerequisites

  • SecurityTrails API key (free tier provides 50 queries/month)
  • Access to DNS provider audit logs (Route53, Azure DNS, Cloudflare, or on-premises DNS)
  • Python 3.9+ with requests library
  • DNS zone file access or AXFR capability for internal zones
  • Historical DNS baseline for comparison

Steps

Step 1: Baseline DNS Records

Export current DNS zone records and establish baseline for all authorized A, AAAA, CNAME, MX, NS, and TXT records.

Step 2: Query Passive DNS History

Use SecurityTrails API to retrieve historical DNS records and identify unauthorized changes, new subdomains, and CNAME records pointing to decommissioned services (dangling CNAMEs).

Step 3: Detect Anomalies

Compare current records against baseline to identify unauthorized modifications, wildcard records that resolve all subdomains, NS delegation changes, and MX record hijacking.

Step 4: Investigate Findings

Correlate DNS anomalies with threat intelligence feeds, check resolution targets against known malicious infrastructure, and validate record ownership.

Expected Output

JSON report listing DNS anomalies with record type, historical changes, risk severity, and remediation recommendations for each finding.