Recon Technique

Recon technique

Goal: map the attack surface with minimal noise, identify high-value entry points, and produce a structured attack plan that drives the next phase (vulnerability scanning, exploitation).

When this technique applies

• External perimeter scoping before a pentest or red team engagement.
• Bug bounty scope expansion: discover assets before prioritizing targets.
• Controlled lab or internal host/service mapping before authorized exploitation testing.
• Pre-exploitation scoping: "where do I spend time?" before vuln scanning.
• API attack-surface mapping before authz, injection, or workflow testing.

Boundary

• vs. osint-technique: OSINT covers identity/person/organization research from public online sources. Recon-technique is attack-surface mapping — domains, IPs, services, endpoints. They overlap at passive DNS and infrastructure pivoting; when recon needs deeper person/company context, load osint-technique.
• vs. network-technique: network-technique covers protocol analysis, PCAP, and in-engagement pivoting. Recon-technique is pre-exploitation surface mapping.
• vs. vuln-scanners: recon produces the target list and service inventory that vuln scanners consume. Do not skip recon and throw scanners at the whole scope.

Initial triage

Before enumerating, classify the scope and decide whether passive or active collection should answer the next question.

• Starting state: do you begin with a domain, organization name, IP range, web target, or partial asset list?
• First questions: what assets are in scope, what can be learned passively first, and what entry-point clusters are most likely to justify active probing?
• Immediate actions: define scope boundaries, run passive collection to build an initial asset map, then promote only the most promising clusters into active validation.
• Tool-family direction: use passive discovery and enrichment first (subfinder, amass, theharvester, asnmap, shodan, gau), then active validation and fingerprinting (dnsx, massdns, masscan, rustscan, nmap, httpx, eyewitness, feroxbuster, gobuster, katana, hakrawler) once a target package exists.
• Escalation rule: do not start vulnerability scanning until recon has produced a prioritized, validated target list.

Agent operating model

Recon is iterative, not a single pass. Each discovery opens new threads.

Loop:
  1. Passive collection — zero target contact.
  2. Catalog assets and identify high-value threads.
  3. Active enumeration — controlled probing of selected targets.
  4. Pivot: new findings trigger new passive queries or deeper active probes.
  5. Repeat until diminishing returns.

Exit when: attack surface is mapped well enough to produce a ranked target list.

Do not move to vulnerability scanning before you have a clear service inventory and a prioritized entry point list.

Phase 1 — Passive recon

Zero direct contact with target infrastructure. All data from public or archived sources.

Goal: build a broad asset map — domains, subdomains, IPs, tech stack — without generating any target-side logs.

1.1 Scope definition

• Define target: root domain(s), IP ranges, organization name, known product brands.
• Note explicit out-of-scope assets.
• Confirm rules of engagement and legal authorization before any action.

1.2 Domain and subdomain discovery

Use certificate transparency, passive DNS, and search engines — no direct DNS queries to target resolvers yet.

Sources to check:

• Certificate Transparency logs (crt.sh, Certspotter, Censys certificate search)
• Passive DNS aggregators (SecurityTrails PDNS, DNSDB, Farsight)
• Search engine dorking: site:target.com, site:*.target.com
• Archive and index: Wayback Machine, Common Crawl, URLScan
• GitHub / GitLab code search: internal domain leaks, subdomains in configs

Tool families:

• offensive-tools/recon/subfinder/ — passive subdomain aggregation from multiple sources
• offensive-tools/osint/amass/ — DNS passive collection + OSINT integrations
• offensive-tools/osint/theharvester/ — emails and subdomains from search engines and DNS sources

1.3 IP and ASN mapping

Map the organization's IP space without scanning it.

• WHOIS and RDAP for IP ranges (ARIN, RIPE, APNIC).
• ASN lookup → BGP prefixes → full IP space.
• Reverse DNS lookups on IPs found in certificate SANs.
• Cloud provider ASN correlation (AWS/GCP/Azure prefix lists — compare with organization WHOIS).

Tool families:

• offensive-tools/recon/asnmap/ — domain/IP/org → full CIDR ranges from ASN data (passive)
• offensive-tools/recon/shodan/ — historical host/service data indexed passively (no direct contact with target)

1.4 Technology and exposure fingerprinting

Identify tech stack, service versions, and historical exposure without touching the target.

• Shodan/Censys historical banners for discovered IP ranges.
• GitHub / GitLab: search for secrets, config leaks, internal domain references.
• Job postings: infer stack from listed technologies (AWS, Spring Boot, PostgreSQL…).
• Wayback Machine: discover dead endpoints, old parameter structures, removed admin paths.

Tool families:

• offensive-tools/recon/shodan/ — historical exposure, open ports, banners, certificates
• offensive-tools/recon/gau/ — known URLs from Wayback, Common Crawl, URLScan per domain

1.5 Passive phase output

Produce before moving to active:

• Subdomain list (confirmed + unresolved candidates)
• IP ranges and ASNs attributed to target
• Tech stack hypothesis per major asset
• Historical exposure signals (old endpoints, leaked configs, dead admin paths)

Phase 2 — Active recon

Controlled direct contact with target infrastructure. Generates logs on target side — scope and pace within authorization limits.

Goal: resolve the passive asset map into a concrete service inventory — open ports, service versions, web endpoints, and ranked attack surface.

2.1 DNS resolution and validation

Resolve the passive subdomain list. Filter dead hosts and wildcard noise before deeper work.

Tool families:

• offensive-tools/recon/dnsx/ — bulk DNS resolution, wildcard detection, filtering
• offensive-tools/recon/massdns/ — high-throughput DNS resolution and brute-force

After initial resolution, expand with active brute-force: use permutation generators (altdns, gotator) to derive candidates from confirmed subdomains (dev-app, app-staging, v2-api), then brute-force resolve with validated resolvers (puredns, shuffledns). Permutation expansion finds assets that passive sources miss. See references/active-recon.md.

2.2 Port sweep

Fast breadth-first sweep across confirmed IP space. Identify open ports — do not probe services yet.

• Start with top-1000 or common-service ports for speed.
• Full-port sweep only on hosts confirmed as high value from passive phase.

Tool families:

• offensive-tools/network/masscan/ — ultra-fast TCP/UDP sweep over large ranges
• offensive-tools/network/rustscan/ — fast discovery with optional nmap handoff

2.3 Service and version enumeration

Deep scan on ports identified in sweep. Version detection, banner grab, default script set.

Tool families:

• offensive-tools/network/nmap/ — version detection, NSE scripts, OS fingerprint

2.4 HTTP fingerprinting and visual triage

For every web-accessible host: status, title, tech stack, redirect chain, TLS metadata. Screenshot for visual ranking of large scopes.

Tool families:

• offensive-tools/recon/httpx/ — HTTP probing at scale: status, title, tech, TLS
• offensive-tools/recon/eyewitness/ — screenshot all HTTP services for visual triage

Detect WAFs and security controls during this phase — before content discovery or parameter fuzzing. httpx -tech-detect surfaces common WAFs inline; dedicated WAF fingerprinting identifies vendor and product for targeted bypass strategy. Adjust tooling (lower rate, evasion headers, tamper scripts) before probing WAF-protected hosts.

Tool families:

• offensive-tools/recon/wafw00f/ — WAF vendor fingerprinting; run per high-value host before injection testing

2.5 Web content discovery

Discover hidden endpoints, admin panels, APIs, and exposed files on confirmed web hosts. Target the highest-value hosts first.

Tool families:

• offensive-tools/recon/feroxbuster/ — recursive content and endpoint brute-force
• offensive-tools/recon/gobuster/ — directory and file enumeration

2.6 URL and parameter harvesting

Collect known URLs and parameters from crawl, JS analysis, and public archives for confirmed live hosts.

Tool families:

• offensive-tools/recon/katana/ — JS-aware web crawler; headless mode for SPA/React/Angular apps
• offensive-tools/recon/hakrawler/ — fast link extraction from static HTML
• offensive-tools/recon/gau/ — passive URL harvest per live host (Wayback, URLScan, Common Crawl)

For REST, GraphQL, and real-time APIs, convert raw routes into an auth-aware inventory before probing. Map methods, documented vs observed sources, trust boundaries, object identifiers, and high-risk parameters; see references/api-recon.md.

2.7 Cloud asset discovery

Modern targets host storage, APIs, and internal tooling in cloud providers outside their own WHOIS/ASN footprint. Shadow IT, dev environments, and data exports frequently appear here.

Passive (no direct contact):

• Search CT logs for cloud-specific subdomain patterns: target.s3.amazonaws.com, target.blob.core.windows.net, target.storage.googleapis.com.
• Query GrayhatWarfare for publicly indexed buckets matching the organization name or product names.
• Extract cloud provider indicators from TXT records (SPF/SES tokens → AWS SES, Google Workspace, etc.).

Active:

• Derive bucket name candidates from organization name, product names, and confirmed subdomains.
• Test discovered bucket candidates for public read/write access.
• Confirm cloud provider per IP range (cross-reference AWS/GCP/Azure prefix lists — see passive-recon.md).
• Use permutation wordlists from known subdomains (altdns, gotator) to generate bucket name candidates before testing.

Tool families:

• s3scanner — enumerate and test S3 bucket permissions (no dedicated skill — pip install s3scanner, then s3scanner scan --buckets candidates.txt)
• cloud_enum — multi-cloud enumeration across S3, Azure Blobs, GCP Storage (no dedicated skill — python cloud_enum.py -k orgname)

See references/cloud-recon.md for detailed patterns and naming strategies.

Transition model

Passive → Active

Move when:

• Subdomain list is stable (two to three passes return no new unique results).
• At least one high-value target cluster is identified.
• IP space attribution is bounded.

Stay in passive when:

• New subdomains still appear rapidly (scope not bounded).
• Active authorization is not yet confirmed.

Active recon → Vulnerability scanning

Move when:

• Service inventory per host is stable (port + version + web tech known).
• At least 3-5 prioritized entry points are identified with specific rationale.
• Content discovery on key web hosts is complete.
• A target package is ready for vuln-search: exact asset, service, web metadata, auth boundary, candidate scanner, and priority rationale.

Attack plan output

Recon ends when the agent produces this structured output:

Asset inventory

Entry point ranking

Rank by:

• Exposure surface: public-facing, unauthenticated, legacy tech
• Data value: admin access, credential endpoints, file upload, API keys
• Historical signals: leaked configs, known CVEs for detected versions, dead paths still live

Next-phase recommendations

Per high-priority target, specify:

• Suggested vuln scanner or technique (e.g., nuclei with matched templates, sqlmap on form endpoints)
• Detected service version → relevant CVE search scope
• Manual investigation areas (e.g., admin panel requires auth bypass testing, file upload requires extension bypass)

Use references/handoff-to-vuln-search.md before switching to vuln-search-technique; it defines the minimum target package and stop conditions.

Quality gates

• Passive phase complete before active probing starts.
• DNS resolution validated — no stale or dead hosts in active target list.
• Port sweep rate and scope confirmed within authorization limits.
• HTTP fingerprinting done on all live web hosts before content discovery.
• Attack plan specifies exact targets with rationale, not vague categories.

Anti-patterns

• Starting vuln scanners before completing service inventory.
• Running content discovery on the entire IP range (pick targets from fingerprinting first).
• Treating Shodan results as ground truth without active confirmation.
• Expanding scope during active phase without re-checking authorization.
• Reporting every subdomain found instead of ranking by attack surface value.
• Confusing recon with OSINT — person/identity research is a different phase.

Resources

• references/passive-recon.md — passive source catalog, Google dork patterns, GitHub search operators, Wayback/archive strategy, subdomain enumeration and permutation candidate preparation.
• references/active-recon.md — port sweep profiles, DNS brute-force and permutation commands, WAF detection, service enumeration patterns, HTTP fingerprinting workflow, content discovery strategy, URL/parameter harvesting.
• references/cloud-recon.md — cloud asset discovery for AWS/Azure/GCP: bucket enumeration, cloud subdomain patterns, metadata SSRF, multi-cloud tooling.
• references/api-recon.md — API inventory, trust-boundary labeling, auth-style mapping, parameter risk profiling, and prioritized test-matrix generation.
• references/handoff-to-vuln-search.md — readiness gate and target package for scanner/manual vulnerability discovery.