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cmu.edu

Name: cmu.edu Email Security Posture Assessment
Creator: RacterMX

Posture Score: 65/100

Scanned May 17, 2026 at 8:12 PM UTC

Identity

Attack Surface

Reputation

Identity Findings

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

External report destination not authorized: andrew.cmu.edu

The rua= URI sends reports to andrew.cmu.edu, but no authorization record exists at cmu.edu._report._dmarc.andrew.cmu.edu. Reports will be silently dropped by compliant receivers.

💡 Ask the owner of andrew.cmu.edu to publish a TXT record at cmu.edu._report._dmarc.andrew.cmu.edu containing 'v=DMARC1'.

high

Subdomains have no DMARC enforcement

sp=none explicitly allows unauthenticated mail from subdomains.

💡 Add sp=reject (or sp=quarantine) to your DMARC record to protect subdomains.

high

DMARC policy is monitoring-only (p=none)

The p=none policy only monitors; it does not instruct receivers to quarantine or reject unauthenticated mail.

💡 Upgrade to p=quarantine or p=reject after reviewing aggregate reports.

medium

External DMARC report destination not authorized: andrew.cmu.edu

The rua= URI points to andrew.cmu.edu but no authorization record exists at cmu.edu._report._dmarc.andrew.cmu.edu.

💡 Ask the owner of andrew.cmu.edu to publish a TXT record at cmu.edu._report._dmarc.andrew.cmu.edu with 'v=DMARC1'.

medium

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.cmu.edu/.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) 'nsauth-master.net.cmu.edu' does not return authoritative answers.

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

medium

No CAA records found

No CAA records are configured. Any certificate authority can issue certificates for this domain.

💡 Add CAA records to restrict certificate issuance. Example: 0 issue "letsencrypt.org"

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@cmu.edu").

low

Very low TTL on DMARC record: 253s

The DMARC record has a TTL of 253s 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

SPF record length OK (32 bytes)

SPF record is within safe DNS packet size 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

No deprecated DMARCbis tags present

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

pass

ARC support likely available

MX server software appears to support ARC headers for authentication preservation.

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

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

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

Shared/free email hosting detected: ASPMX.L.GOOGLE.COM

The MX record points to a known shared or free email hosting provider.

informational

Shared/free email hosting detected: ALT1.ASPMX.L.GOOGLE.COM

The MX record points to a known shared or free email hosting provider.

informational

Shared/free email hosting detected: ALT2.ASPMX.L.GOOGLE.COM

The MX record points to a known shared or free email hosting provider.

informational

Shared/free email hosting detected: ALT3.ASPMX.L.GOOGLE.COM

The MX record points to a known shared or free email hosting provider.

informational

Shared/free email hosting detected: ALT4.ASPMX.L.GOOGLE.COM

The MX record points to a known shared or free email hosting provider.

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 ASPMX.L.GOOGLE.COM

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 5 different /16 networks, providing good diversity.

informational

SOA record parameters

Serial: 20494530, Refresh: 900s, Retry: 450s, Expire: 3600000s, Min TTL: 21600s

informational

Attack Surface Findings

NSEC records enable zone walking

The domain uses NSEC records for DNSSEC authenticated denial of existence. NSEC records can be walked to enumerate all names in the zone, effectively disclosing the entire zone contents.

💡 Switch from NSEC to NSEC3 with opt-out to prevent zone enumeration. Use NSEC3 with a random salt and sufficient iterations.

high

Domain enumerability: high

The domain is highly enumerable. Zone transfers, NSEC zone walking, or a combination of factors make it easy to discover all DNS records.

💡 Restrict zone transfers, use NSEC3 instead of NSEC, consider wildcard certificates to reduce CT log exposure, and implement rate limiting on DNS queries.

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

LOC record exposes geographic location

A LOC record for cmu.edu reveals the physical location of infrastructure. This aids targeted attacks.

💡 Remove the LOC record from public DNS unless geographic information is intentionally published.

medium

DNS ANY query returns 66 record(s)

The DNS server responds to ANY queries with 66 record(s), creating significant DNS amplification risk.

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

medium

NSEC used instead of NSEC3 (zone enumeration possible)

The domain uses NSEC records for authenticated denial of existence. NSEC allows zone walking.

💡 Migrate from NSEC to NSEC3 to prevent zone enumeration.

medium

Software/version information in TXT record

A TXT record contains a software identifier or version string: "26.39.0".

💡 Review TXT records and remove unnecessary software version information.

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

8 subdomain(s) discovered for cmu.edu

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 cmu.edu and its subdomains. Each certificate reveals subdomain names.

informational

DNSSEC is enabled

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

informational

Reputation Findings

Missing domain locks: clientTransferProhibited, clientDeleteProhibited

Domain cmu.edu is missing protective locks: clientTransferProhibited, clientDeleteProhibited.

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

high

HSTS enabled but missing preload directive on cmu.edu

Strict-Transport-Security: max-age=300

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

low

Not listed on any DNS blacklists

Domain and MX IPs checked against 55 DNSBLs — no listings found.

pass

security.txt present

Found security.txt at https://cmu.edu/.well-known/security.txt.

pass

TLS certificate valid for 246 days

Certificate for cmu.edu expires on 2027-01-18.

pass

Certificate issued by InCommon RSA Server CA 2

The certificate for cmu.edu is issued by a third-party CA.

pass

Signature algorithm: rsa-sha256

The certificate for cmu.edu uses an acceptable signature algorithm.

pass

RSA key: 2048 bits

The certificate for cmu.edu uses an adequate RSA key of 2048 bits.

pass

SCTs present in certificate

The certificate for cmu.edu contains Signed Certificate Timestamps.

pass

No weak ciphers detected

No known weak cipher suites detected on cmu.edu.

pass

Domain valid for 439 days

Domain cmu.edu expires on 2027-07-31.

pass

No disposable email provider MX records

MX records for cmu.edu do not match known disposable email provider patterns.

pass

No wildcard MX records

No wildcard MX records detected for cmu.edu.

pass

TLD has good reputation

The .edu 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 (ASPMX.L.GOOGLE.COM) uses TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 including Forward Secrecy.

pass

SMTP banner from hosted mail provider

The MX (ASPMX.L.GOOGLE.COM) is a hosted mail service. Banner alignment is managed by the provider and not actionable by the domain owner.

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.cmu.edu

HTTPS request to https://webmail.cmu.edu failed or timed out.

informational

WHOIS registration data

Registrar: Unknown | Created: Unknown | Expires: 2027-07-31 | Updated: 2026-01-30

informational

WHOIS privacy protection not detected

Domain cmu.edu does not appear to have WHOIS privacy protection. Registrant details may be publicly visible.

informational

Could not determine domain age

WHOIS creation date could not be parsed for cmu.edu.

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: mu.edu (has MX!), cu.edu (has MX!), mcu.edu (has MX!), dmu.edu (has MX!), fmu.edu (has MX!)

18 registered lookalike domain(s) that could be used for phishing against your brand. Showing top 5 of 18. 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: none

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: none

⚠️ 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: ASPMX.L.GOOGLE.COM

PTR record proves mail server legitimacy

MX: ASPMX.L.GOOGLE.COM Mail server at 209.85.202.27 → PTR Record Reverse DNS: dg-in-f27.1e100.net

Mail Server Identity: ALT1.ASPMX.L.GOOGLE.COM

PTR record proves mail server legitimacy

MX: ALT1.ASPMX.L.GOOGLE.COM Mail server at 173.194.76.26 → PTR Record Reverse DNS: ws-in-f26.1e100.net

Mail Server Identity: ALT2.ASPMX.L.GOOGLE.COM

PTR record proves mail server legitimacy

MX: ALT2.ASPMX.L.GOOGLE.COM Mail server at 142.250.102.26 → PTR Record Reverse DNS: rb-in-f26.1e100.net

Mail Server Identity: ALT3.ASPMX.L.GOOGLE.COM

PTR record proves mail server legitimacy

MX: ALT3.ASPMX.L.GOOGLE.COM Mail server at 192.178.213.27 → PTR Record Reverse DNS: yugrqzs-in-f27.1e100.net

Mail Server Identity: ALT4.ASPMX.L.GOOGLE.COM

PTR record proves mail server legitimacy

MX: ALT4.ASPMX.L.GOOGLE.COM Mail server at 142.251.127.27 → PTR Record Reverse DNS: lcfrai-in-f27.1e100.net

Mail Server Reputation: ASPMX.L.GOOGLE.COM