assfin

README

assfin

Recursive, passive subdomain reconnaissance and HTTP probing toolkit

Features • Installation • Usage • Running assfin • Querying Results • HTML Reports • Library Usage • How It Works

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assfin is a passive reconnaissance and asset intelligence tool that automates recursive subdomain discovery and HTTP service probing in a single Go binary. It queries passive sources for a target root domain using subfinder, iteratively recurses across every discovered subdomain layer until no new targets emerge, and immediately verifies live services with httpx.

All results are deduplicated and tracked in a persistent SQLite database with historical timeline metadata (first_seen, last_seen, new), which can be queried directly via CLI, piped into downstream tools like nuclei, or exported into a standalone offline HTML dashboard.

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Features

• Recursive Passive Discovery: Iteratively enumerates multi-level subdomains by feeding newly uncovered assets back into passive discovery rounds until exhaustion.
• WAF-Safe Probing: Pre-configured with conservative request rates (30 req/s, 25 workers) and no DNS brute-forcing to avoid rate limits or disruption.
• Heuristic WAF Detection: Detects Cloudflare, Akamai, Imperva, and other WAFs using IP CIDR matching (cdncheck) and response headers/cookies without sending attack payloads.
• Persistent Asset Database: Tracks target history across runs in SQLite, automatically identifying newly appeared hosts and marking unreachable endpoints.
• Pipe-Friendly Architecture: Supports table, list, and json output streams to integrate cleanly with nuclei, katana, or custom automation pipelines.
• Self-Contained HTML Reports: Produces portable, single-file offline dashboards with status filters, technology tags, and WAF categorization.
• Go Library / SDK: Clean programmatic API through pkg/runner for direct integration into custom Go tools.

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Installation

Using Go

go install -v github.com/aktezed/assfin/cmd/assfin@latest

From Source

git clone https://github.com/aktezed/assfin.git
cd assfin
make build
# Binary is compiled to bin/assfin

Pre-built Binaries

Pre-compiled releases for macOS, Linux, and Windows are available on the Releases page.

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Usage

assfin -h

This displays help for all available flags and command modes:

assfin - recursive passive subdomain recon & asset intelligence

Usage:
  assfin [flags]

Flags:
INPUT:
   -d, -domain string  root domain to scan
   -dL, -list string   file with root domains, one per line

STORAGE:
   -db string  SQLite output (default <domain>.db, or assfin.db with -dL)

RECURSION:
   -depth int         recursion rounds after root (-1 = auto-increase until nothing new is found, 0 = root only) (default -1)
   -max-hosts int     stop enumerating a root after this many hosts (0 = no cap) (default 5000)
   -exclude string[]  out-of-scope hosts/suffixes (comma-separated)

SUBFINDER:
   -sf-timeout int               subfinder per-source timeout in seconds (default 15)
   -sf-max-time int              subfinder max minutes per domain (default 2)
   -sf-concurrency int           subdomains enumerated in parallel (default 5)
   -pc, -provider-config string  subfinder provider-config.yaml

PROBING:
   -rate int     httpx max requests per second (default 30)
   -threads int  httpx threads (default 25)
   -timeout int  httpx request timeout in seconds (default 7)
   -follow       follow redirects when probing
   -no-probe     enumerate only, skip httpx

QUERY / FILTER:
   -q, -query                 run in query mode against existing database
   -name string[]             host contains (comma-separated for OR)
   -tech string[]             technology, e.g. -tech nginx,php
   -waf                       only hosts behind a WAF
   -no-waf                    only hosts with no WAF detected
   -waf-name string           WAF name contains, e.g. cloudflare
   -alive                     only hosts that answered HTTP(S)
   -dead                      only hosts that did not answer
   -status string             status codes, e.g. 200,403
   -new                       only hosts first seen in the latest scan
   -filter-depth int          label depth: 1 = x.root, 2 = y.x.root (default -1)
   -root string               only this root domain
   -sql string                raw read-only SQL, e.g. "SELECT host, tech FROM hosts WHERE status=401"
   -o, -output-format string  output: table, list, json (default "table")

REPORT:
   -report      generate HTML report from database (or after scan)
   -out string  HTML report output path (default report.html)

GENERAL:
   -s, -silent  silent mode: output only results
   -version     show version

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Running assfin

Scan Mode

Scan a single root domain and store output in example.com.db:

assfin scan -d example.com

Scan and generate an interactive HTML report in the same run:

assfin scan -d example.com -report
assfin scan -d example.com -report -out dashboard.html

Scan multiple root domains from an input file:

assfin scan -dL roots.txt -db targets.db

Exclude out-of-scope subdomains or domains:

assfin scan -d example.com -exclude staging.example.com,internal.example.com

WAF-Safe Fast Defaults

Flag	Default	Description
-depth	-1 (auto)	Automatically increases depth (1 -> 2 -> 3...) until no new hosts are found (0 = root only)
-max-hosts	5000	Max hosts to discover per root domain before stopping
-sf-concurrency	5	Number of subdomains enumerated concurrently
-sf-timeout	15s	Subfinder per-source timeout
-sf-max-time	2m	Subfinder total timeout per domain
-rate	30	Maximum HTTP requests per second for httpx
-threads	25	Worker thread count for httpx
-timeout	7s	HTTP request timeout
-follow	false	Follow HTTP redirects
-no-probe	false	Passive enumeration only; skips HTTP probing

[!NOTE] Enumeration uses passive sources only (e.g. crt.sh, VirusTotal, AlienVault) and never queries the target's authoritative DNS servers. The only packets sent to target infrastructure are standard HTTP/HTTPS GET requests from httpx governed by -rate.

Passive API Configuration

assfin automatically loads subfinder's standard configuration at ~/.config/subfinder/provider-config.yaml. You can also specify an alternate config path with -pc:

assfin scan -d example.com -pc /path/to/provider-config.yaml

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Querying Results

Query mode allows fast filtering against an existing SQLite database without making any network requests.

# Filter alive hosts with no WAF detected
assfin query -db example.com.db -alive -no-waf

# Filter by technology stack and HTTP response code
assfin query -db example.com.db -tech wordpress -status 200

# Filter hosts containing specific keywords
assfin query -db example.com.db -name api,admin,staging

# Filter by specific WAF vendor
assfin query -db example.com.db -waf-name cloudflare

# Filter newly discovered hosts from the latest scan and pipe to nuclei
assfin query -db example.com.db -new -o list | nuclei -t cves/

# Filter by subdomain label depth (1 = sub.domain.com, 2 = deep.sub.domain.com)
assfin query -db example.com.db -filter-depth 2 -o json

# Run raw read-only SQL queries
assfin query -db example.com.db -sql "SELECT host, title, status FROM hosts WHERE status = 403"

Database Schema

The hosts table contains the following fields:

host, root, depth, sources, first_seen, last_seen, first_scan, last_scan, alive, url, status, title, server, tech, ips, cdn, waf, length

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HTML Reports

Generate a self-contained, offline-compatible HTML dashboard from an existing database:

assfin report -db example.com.db
assfin report -db example.com.db -out audit.html

The generated report features:

• Visual Breakdown: Tri-color distribution bar showing reachable without WAF, behind WAF, and unresponsive hosts.
• Interactive Filtering: Instant keyword search, HTTP status code filtering, and technology tag filtering.
• Host Details: Expandable drawer for each host containing resolved IPs, response headers, detected technologies, and titles.

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Library Usage

assfin can be used programmatically in your Go projects using pkg/runner:

package main

import (
	"context"
	"log"

	"github.com/aktezed/assfin/pkg/runner"
	"github.com/aktezed/assfin/pkg/types"
)

func main() {
	options := &types.Options{
		Command: "scan",
		Domain:  "example.com",
		DBPath:  "example.db",
		Depth:   2,
	}

	r, err := runner.NewRunner(options)
	if err != nil {
		log.Fatal(err)
	}
	defer r.Close()

	if err := r.Run(context.Background()); err != nil {
		log.Fatal(err)
	}
}

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How It Works

Recursive Passive Discovery

[Target Domain] ──▶ (Round 0: Subfinder Passive Sources)
                           │
                           ▼
                  [Discovered Subdomains]
                           │
                           ▼
              (Round 1..N: Recursive Re-Feed)
              Repeats until 0 new hosts discovered
                           │
                           ▼
                     [Deduplication]
                           │
                           ▼
               [HTTPX WAF-Safe Probing]
                           │
                           ▼
                   [SQLite Storage]

1. Initial Harvest: assfin enumerates the root domain across dozens of passive sources.
2. Recursive Expansion: Any newly identified subdomain is added to the crawl queue and fed back into passive sources. Rounds continue automatically until no new subdomains appear (or -depth limit is reached).
3. Controlled Probing: Discovered hosts are probed using httpx with WAF-safe concurrency (-rate 30).
4. State Persistence: Hosts are written to SQLite, preserving first-seen and last-seen timestamps to track asset changes over time.

Heuristic WAF Detection

WAF detection runs entirely without intrusive payloads:

1. IP Range Matching: Matches remote IPs against known WAF/CDN CIDR ranges (Cloudflare, Akamai, Imperva, Fastly, CloudFront, etc.) via cdncheck.
2. Passive Header & Cookie Inspection: If IP checks are inconclusive, checks response headers (e.g. cf-ray, x-sucuri-id) and cookies (incap_ses_, __cf_bm) collected during probing.

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Limitations

• Passive Data Dependency: Discovery relies entirely on passive sources. If an asset has never appeared in certificate transparency logs, DNS datasets, or public indices, passive recursion will not find it.
• Active DNS Permutations: assfin does not perform active DNS brute-forcing or wordlist permutations.
• Depth Saturation: Most passive sources index all known hostnames in the first pass; recursion past depth 2 rarely yields substantial new hosts on standard targets.

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License

assfin is distributed under the MIT License.