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DMARC/SPF/DKIM check, email spoofing, SMTP test, and security header analysis
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Full WSTG-aligned web application pentest — 12-phase methodology from information gathering through reporting, with concrete commands, expected outputs, pitfalls, and verification per phase.
Attack SAML SSO via XSW, signature strip, metadata extract.
Use when two or more verified findings may combine into a higher-impact authorized attack path.
Based on SOC occupation classification
Showing SKILL.md
| name | email-security |
| description | DMARC/SPF/DKIM check, email spoofing, SMTP test, and security header analysis |
| version | 1.1.0 |
| revision_date | "2026-07-25T00:00:00.000Z" |
| license | MIT |
| category | recon |
| tags | ["email","SPF","DKIM","DMARC","spoofing","SMTP","recon"] |
# SPF
dig +short TXT $target | grep "v=spf1"
# DMARC
dig +short TXT _dmarc.$target
# DKIM (common selector: google)
dig +short TXT google._domainkey.$target
# MX
dig +short MX $target
| Config | Meaning | Risk |
|---|---|---|
| v=spf1 ~all (softfail) | SPF suggests blocking but doesnt enforce | Spoofed emails may pass |
| v=spf1 ?all (neutral) | SPF does nothing | Totally permissive |
| v=spf1 include:amazonses.com ~all | SES can send as domain | Any AWS SES account can spoof |
| v=DMARC1; p=none | DMARC disabled | Zero spoofing protection |
| v=DMARC1; p=quarantine | Failed emails go to spam | Partial protection |
| v=DMARC1; p=reject | Failed emails rejected | Full protection |
| DKIM missing | No cryptographic signature | Email can be forged |
# Test SMTP relay
timeout 3 bash -c 'exec 3<>/dev/tcp/TARGET/25; head -1 <&3'
# Send spoofed email via open relay (swaks)
swaks --to victim@target.com --from admin@target.com --server TARGET --body "Spoofed email"
| Header | Value | Meaning |
|---|---|---|
| Authentication-Results | spf=pass | SPF passed |
| Authentication-Results | spf=fail | SPF failed |
| Authentication-Results | dmarc=pass | DMARC passed |
| Authentication-Results | dmarc=fail | DMARC failed |
| Authentication-Results | dkim=pass | DKIM passed |
| Received-SPF | Pass | Sender authorized |
| Received-SPF | Softfail | Sender not fully authorized |
| Received-SPF | Fail | Sender not authorized |
| ARC-Authentication-Results | Authentication chain |
With v=spf1 include:amazonses.com ~all:
Real-world case (CRITICAL): Political party -- DMARC p=none on both domains (DOMAIN_PLACEHOLDER_A, DOMAIN_PLACEHOLDER_B). SPF with include:amazonses.com (any SES account can send as the domain). Total email spoofing.
| Issue | Solution |
|---|---|
| SPF lookup limit | DNS has 10 lookup limit for SPF includes |
| DKIM selector unknown | Try common selectors: google, selector1, selector2, 2022, 2023 |
| DMARC reporting | rua=mailto: may leak authentication results to third party |
# Verify email spoofing is possible
# Send test email and check headers:
dig +short TXT _dmarc.target.com
# If p=none -> confirmed spoofable