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nih.gov

Name: nih.gov Email Security Posture Assessment
Creator: RacterMX

Posture Score: 61/100

Scanned May 23, 2026 at 11:47 PM UTC

Identity

Attack Surface

Reputation

Identity Findings

Weak DKIM RSA key (~1296 bits) for selector 'selector1'

RSA keys shorter than 2048 bits are considered weak. Current key is approximately 1296 bits.

💡 Generate a new 2048-bit (or larger) RSA key pair and update the DKIM record.

high

Weak DKIM RSA key (~1296 bits) for selector 'k1'

RSA keys shorter than 2048 bits are considered weak. Current key is approximately 1296 bits.

💡 Generate a new 2048-bit (or larger) RSA key pair and update the DKIM record.

high

Weak DKIM RSA key (~1296 bits) for selector 's2'

RSA keys shorter than 2048 bits are considered weak. Current key is approximately 1296 bits.

💡 Generate a new 2048-bit (or larger) RSA key pair and update the DKIM record.

high

No MTA-STS record found

Without MTA-STS, mail transport encryption cannot be enforced and is vulnerable to downgrade attacks.

💡 Publish a _mta-sts TXT record and host a policy file at https://mta-sts.nih.gov/.well-known/mta-sts.txt

medium

STARTTLS without MTA-STS or DANE protection

STARTTLS alone is vulnerable to downgrade attacks. Neither MTA-STS nor DANE is configured to enforce encryption.

💡 Deploy MTA-STS and/or DANE to protect against STARTTLS stripping attacks.

medium

SOA MNAME is not authoritative

The primary nameserver (MNAME) 'nihblox6.nih.gov' does not return authoritative answers.

💡 Update the MNAME field to point to an authoritative nameserver for this zone.

medium

No TLS-RPT record found

Without TLS-RPT, you will not receive reports about TLS negotiation failures.

💡 Publish a _smtp._tls TXT record (e.g. "v=TLSRPTv1; rua=mailto:tls-reports@nih.gov").

low

ARC support not detected

No evidence of ARC (Authenticated Received Chain) support on MX servers. Forwarded messages may lose authentication.

💡 Consider enabling ARC signing on your mail servers to preserve authentication through forwarding.

low

No CAA iodef tag configured

No iodef tag is present in the CAA records. CA policy violation reports will not be sent.

💡 Add an iodef CAA record. Example: 0 iodef "mailto:security@example.com"

low

Very low TTL on TXT records: 224s

57 TXT records have a TTL of 224s or less (below 300s).

💡 Increase the TTL to at least 300 seconds unless frequent changes are expected.

low

Very low TTL on SPF record: 224s

The SPF record has a TTL of 224s or less (below 300s).

💡 Increase the TTL to at least 300 seconds unless frequent changes are expected.

low

SPF record is valid

The SPF record is properly configured with valid syntax and within lookup limits.

pass

DKIM cryptographic configuration is compliant

No RFC 8301 compliance issues detected in DKIM key configuration.

pass

DKIM key strength indicates modern key management

All DKIM keys use RSA-2048+ or Ed25519, consistent with current best practices.

pass

All external report destinations authorized

External DMARC report destinations have valid authorization records per RFC 7489 §7.1.

pass

Subdomains protected (sp=reject)

DMARC subdomain policy enforces quarantine or reject on unauthenticated subdomain mail.

pass

No deprecated DMARCbis tags present

The DMARC record does not use any tags deprecated in DMARCbis (pct, rf, ri).

pass

MX records are valid

All MX records are properly configured.

pass

Meets bulk sender authentication requirements

Domain has SPF, DKIM, and DMARC — meeting Google/Yahoo 2024 bulk sender requirements for email authentication.

pass

SMTP security checks passed

No open relay, VRFY/EXPN, or banner disclosure issues detected.

pass

SMTP RFC 5321 compliance checks passed

The mail server accepts postmaster@ and abuse@ and uses a valid FQDN in EHLO.

pass

IPv6 readiness is good

IPv6 records are present and properly configured.

pass

NS delegation is properly configured

All nameservers are responsive, consistent, and properly secured.

pass

DNS responses are consistent across all nameservers

All authoritative nameservers return consistent answers with proper AA flags.

pass

SPF record is 287 bytes (multi-string TXT)

The SPF record exceeds 255 bytes and requires multi-string TXT encoding. Most modern resolvers handle this correctly.

informational

DKIM2 not detected

No DKIM key record with v=2 was found across common selectors. DKIM2 is an emerging standard and not yet widely deployed.

informational

DMARC alignment: adkim=r, aspf=r

DKIM alignment is relaxed, SPF alignment is relaxed.

informational

DMARC failure reporting: fo=1

Failure reports generated when any authentication mechanism fails.

informational

DMARCbis np tag absent

The DMARC record does not include the np (non-existent subdomain policy) tag. Consider adding np=reject to protect non-existent subdomains under DMARCbis.

informational

DMARCbis psd tag absent

The DMARC record does not include the psd (public suffix domain) indicator. Consider adding psd=n to explicitly identify this as an organizational domain.

informational

REQUIRETLS not advertised

The primary MX does not advertise REQUIRETLS (RFC 8689). This is an emerging standard — MTA-STS and DANE provide adequate TLS enforcement for most deployments.

informational

No DANE/TLSA records found

DANE is not configured for any MX server. This is optional but provides strong certificate binding.

informational

No BIMI record found

BIMI is not configured. Your brand logo will not display in supporting email clients.

informational

Open mail ports on nihcesxway3.hub.nih.gov

Detected open mail-related ports: 25

informational

RFC 8058 one-click unsubscribe assessment

DKIM signing is configured. RFC 8058 compliance depends on List-Unsubscribe and List-Unsubscribe-Post headers being included in outbound messages and DKIM signatures.

informational

MX IP network diversity

MX IPs span 2 different /16 networks, providing good diversity.

informational

SOA record parameters

Serial: 930345, Refresh: 10800s, Retry: 1080s, Expire: 2592000s, Min TTL: 900s

informational

Authorized certificate authorities

CAA records restrict certificate issuance to: amazon.com, digicert.com, entrust.net, globalsign.com, godaddy.com, identrust.com, letsencrypt.org, sectigo.com

informational

Attack Surface Findings

Weak DNSSEC RSA key: 336 bits

The DNSKEY uses an RSA key of 336 bits, below the recommended 2048 bits.

💡 Generate a new DNSKEY with at least 2048-bit RSA or migrate to ECDSA/Ed25519.

high

Weak DNSSEC RSA key: 336 bits

The DNSKEY uses an RSA key of 336 bits, below the recommended 2048 bits.

💡 Generate a new DNSKEY with at least 2048-bit RSA or migrate to ECDSA/Ed25519.

high

Weak DNSSEC RSA key: 336 bits

The DNSKEY uses an RSA key of 336 bits, below the recommended 2048 bits.

💡 Generate a new DNSKEY with at least 2048-bit RSA or migrate to ECDSA/Ed25519.

high

Weak DNSSEC RSA key: 336 bits

The DNSKEY uses an RSA key of 336 bits, below the recommended 2048 bits.

💡 Generate a new DNSKEY with at least 2048-bit RSA or migrate to ECDSA/Ed25519.

high

DNS ANY query returns 105 record(s)

The DNS server responds to ANY queries with 105 record(s), creating significant DNS amplification risk.

💡 Configure the DNS server to refuse or minimize ANY query responses per RFC 8482.

medium

Domain enumerability: low

The domain has low enumerability. Proper NSEC3 configuration and limited CT exposure reduce the attack surface.

low

All MX records resolve correctly

No dangling MX records detected — all MX hostnames resolve to valid IP addresses.

pass

Explicit MX records present

The domain has explicit MX records — no implicit A-record fallback delivery.

pass

No internal information leakage detected

No non-routable IP addresses or internal references were found in public DNS records.

pass

No email autodiscovery endpoints detected

No Microsoft Autodiscover, Mozilla Autoconfig, or email SRV records were found.

pass

14 subdomain(s) discovered for nih.gov

Subdomains were enumerated via Certificate Transparency logs, DNS wordlist brute-forcing, and DNS record analysis.

informational

0 certificate(s) found in CT logs

Certificate Transparency logs contain 0 certificate(s) for nih.gov and its subdomains. Each certificate reveals subdomain names.

informational

NSEC3 authenticated denial of existence

The domain uses NSEC3 with 10 iteration(s) and salt '5D500E46CEA3E7AF1874'.

informational

DNSSEC is enabled

DNSKEY and/or DS records are present, indicating DNSSEC is configured.

informational

Reputation Findings

Listed on dnsbl.spfbl.net

165.112.13.42 (nihcesxwayst04.hub.nih.gov) is listed on blacklist dnsbl.spfbl.net (response: 127.0.0.4).

💡 Visit the dnsbl.spfbl.net website to request delisting. Investigate the root cause (compromised account, open relay, spam) before requesting removal.

critical

Listed on dnsbl.spfbl.net

165.112.13.46 (nihcesxwayst05.hub.nih.gov) is listed on blacklist dnsbl.spfbl.net (response: 127.0.0.4).

💡 Visit the dnsbl.spfbl.net website to request delisting. Investigate the root cause (compromised account, open relay, spam) before requesting removal.

critical

Missing domain locks: clientDeleteProhibited

Domain nih.gov is missing protective locks: clientDeleteProhibited.

💡 Enable clientTransferProhibited and clientDeleteProhibited locks through your registrar to prevent unauthorized transfers or deletions.

high

HSTS enabled but missing preload directive on nih.gov

Strict-Transport-Security: max-age=31536000

💡 Add the "preload" directive to the HSTS header and submit the domain to hstspreload.org.

low

security.txt present

Found security.txt at https://nih.gov/.well-known/security.txt.

pass

TLS certificate valid for 267 days

Certificate for nih.gov expires on 2027-02-15.

pass

Certificate issued by Go Daddy Secure Certificate Authority - G2

The certificate for nih.gov is issued by a third-party CA.

pass

Signature algorithm: rsa-sha256

The certificate for nih.gov uses an acceptable signature algorithm.

pass

RSA key: 2048 bits

The certificate for nih.gov uses an adequate RSA key of 2048 bits.

pass

SCTs present in certificate

The certificate for nih.gov contains Signed Certificate Timestamps.

pass

No weak ciphers detected

No known weak cipher suites detected on nih.gov.

pass

Domain valid for 90 days

Domain nih.gov expires on 2026-08-22.

pass

No disposable email provider MX records

MX records for nih.gov do not match known disposable email provider patterns.

pass

Domain is 10460 days old

Domain nih.gov was registered 1997-10-02.

pass

No wildcard MX records

No wildcard MX records detected for nih.gov.

pass

TLD has good reputation

The .gov TLD is not on known abuse watchlists.

pass

DMARC reporting destinations look legitimate

DMARC rua/ruf addresses do not point to known URL shortener services.

pass

MX records point to stable infrastructure

No MX records point to known dynamic DNS service domains.

pass

Strong TLS configuration on primary MX

Primary MX (nihcesxway5.hub.nih.gov) uses TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 including Forward Secrecy.

pass

SMTP banner matches infrastructure identity

The SMTP banner (nihcesxwayst03.hub.nih.gov) aligns with the MX hostname (nihcesxwayst03.hub.nih.gov).

pass

Google Safe Browsing DNS check — no flag detected

DNS-based Safe Browsing lookup returned no results. Full verification requires the Google Safe Browsing API key.

informational

Abuse contacts found for MX IPs

Abuse contact information retrieved via abusix.org DNS lookup.

informational

PhishTank — API key required

PhishTank phishing database check requires an API key.

informational

Sender Score — API key required

Sender Score reputation check requires an API key.

informational

Cisco Talos — API key required

Cisco Talos IP reputation check requires an API key.

informational

Could not connect to webmail.nih.gov

HTTPS request to https://webmail.nih.gov failed or timed out.

informational

WHOIS registration data

Registrar: get.gov | Created: 1997-10-02 | Expires: 2026-08-22 | Updated: 2026-03-04

informational

WHOIS privacy protection enabled

Domain nih.gov has WHOIS privacy/redaction enabled.

informational

Bulletproof Hosting Detection — API key required

Checking IPs against known bulletproof hosting providers requires a threat intelligence API key.

informational

Threat Intelligence Feeds — API key required

Checking domain against threat intelligence feeds requires API keys (e.g., VirusTotal, AbuseIPDB).

informational

Typosquat detected: nh.gov (has MX!), nij.gov (has MX!), nih.net (has MX!), nih.org (has MX!), nih.io (has MX!)

8 registered lookalike domain(s) that could be used for phishing against your brand. Showing top 5 of 8. Domains with MX records can send and receive email, making them high-risk phishing vectors.

informational

Dependency Chains

DMARC Authentication Chain (SPF)

DMARC uses SPF to verify that emails come from authorized servers

SPF Record SPF record found and configured → DMARC Policy DMARC policy: reject

DMARC Authentication Chain (DKIM)

DMARC uses DKIM to verify that emails have not been tampered with

DKIM Signature DKIM signature missing → DMARC Policy DMARC policy: reject

⚠️ DKIM signature is missing. DMARC relies on DKIM to verify email integrity and prevent tampering. Without DKIM, DMARC alignment will fail for cryptographic verification.

Mail Server Identity: nihcesxway3.hub.nih.gov

PTR record proves mail server legitimacy

MX: nihcesxway3.hub.nih.gov Mail server at 128.231.90.125 → PTR Record Reverse DNS: nihcesxway3.hub.nih.gov

Mail Server Identity: nihcesxway4.hub.nih.gov

PTR record proves mail server legitimacy

MX: nihcesxway4.hub.nih.gov Mail server at 128.231.90.119 → PTR Record Reverse DNS: nihcesxway4.hub.nih.gov

Mail Server Identity: nihcesxway5.hub.nih.gov

PTR record proves mail server legitimacy

MX: nihcesxway5.hub.nih.gov Mail server at 128.231.90.120 → PTR Record Reverse DNS: nihcesxway5.hub.nih.gov

Mail Server Identity: nihcesxway6.hub.nih.gov

PTR record proves mail server legitimacy

MX: nihcesxway6.hub.nih.gov Mail server at 128.231.90.121 → PTR Record Reverse DNS: nihcesxway6.hub.nih.gov

Mail Server Identity: nihcesxwayst03.hub.nih.gov

PTR record proves mail server legitimacy

MX: nihcesxwayst03.hub.nih.gov Mail server at 165.112.13.34 → PTR Record Reverse DNS: nihcesxwayst03.hub.nih.gov

Mail Server Identity: nihcesxwayst04.hub.nih.gov

PTR record proves mail server legitimacy

MX: nihcesxwayst04.hub.nih.gov Mail server at 165.112.13.42 → PTR Record Reverse DNS: nihcesxwayst04.hub.nih.gov

Mail Server Identity: nihcesxwayst05.hub.nih.gov

PTR record proves mail server legitimacy

MX: nihcesxwayst05.hub.nih.gov Mail server at 165.112.13.46 → PTR Record Reverse DNS: nihcesxwayst05.hub.nih.gov

Mail Server Identity: nihcesxwayst06.hub.nih.gov

PTR record proves mail server legitimacy

MX: nihcesxwayst06.hub.nih.gov Mail server at 165.112.13.54 → PTR Record Reverse DNS: nihcesxwayst06.hub.nih.gov

Mail Server Reputation: nihcesxway3.hub.nih.gov