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Invalid Hostname Validation (CN/SAN Mismatch)

It means the SSL/TLS certificate’s Common Name (CN) or Subject Alternative Name (SAN) does not match the accessed domain. This mismatch indicates that the certificate may not have been legitimately issued for the current host, raising authenticity concerns.

See verdicts firing this signalOpen in API reference
Analyst Q&A

What this signal answers

The questions every analyst asks before acting on this signal.

What it detects01

What does 'Invalid Hostname Validation (CN/SAN Mismatch)' mean in SOC or domain analysis?

It means the SSL/TLS certificate’s Common Name (CN) or Subject Alternative Name (SAN) does not match the accessed domain. This mismatch indicates that the certificate may not have been legitimately issued for the current host, raising authenticity concerns.

Why it matters02

Why is a CN/SAN mismatch considered suspicious in security monitoring?

Because attackers and malicious proxies often present mismatched certificates to intercept or impersonate legitimate traffic. It can also result from expired or misconfigured certificates, but when seen in combination with malicious behaviors, it is a strong red flag.

How analysts use it03

How should SOC analysts interpret hostname validation failures?

Analysts should verify whether the mismatch is due to misconfiguration, expired certificates, or deliberate tampering. In threat contexts, this indicator is frequently associated with phishing kits, fake HTTPS sites, and man-in-the-middle interception attempts.

Often paired with:block_domain
Evidence shape

What Invalid Hostname Validation (CN/SAN Mismatch) looks like in the response

A realistic shape of the entry the engine appends to the risk_signals array when this signal fires. Evidence keys are subgroup-default; per-signal overrides documented in the API reference.

json
{
  "slug": "ssl_host_validation_failed",
  "name": "Invalid Hostname Validation (CN/SAN Mismatch)",
  "group": "http_crawling_history",
  "subgroup": "ssl_behavior",
  "direction": "malicious",
  "evidence": {
    "cert_issued_days_ago": 9,
    "issuer": "letsencrypt",
    "valid_for_days": 90,
    "rotation_count_90d": 3,
    "cert_type": "DV"
  }
}
See in API reference
Siblings

Peers in SSL Behavior

14 other signals share the same subgroup. They detect related behaviors and often co-fire on the same IOC.

Critical SSL Certificate Authentication Failure

It means that the SSL/TLS certificate presented by the domain failed critical validation checks. This can occur due to m…

MaliciousCore
Organization-Validated (OV) SSL Certificate Detected

It means the SSL/TLS certificate of the domain includes verified organizational details that have been authenticated by …

SafeCore
Self-Signed SSL Certificate Detected

It means the domain is using an SSL/TLS certificate that was generated and signed by the same entity, without verificati…

MaliciousCore
Untrusted Certificate Authority (CA) Detected

It means that the SSL/TLS certificate presented by the domain was issued or signed by a Certificate Authority that is no…

MaliciousCore
Show 10 more in SSL Behavior
In the wild

See Invalid Hostname Validation (CN/SAN Mismatch) fire on real IOCs

The Verdict Gallery is a curated stream of real verdicts. Filter by this signal to see exactly which IOCs it caught, what other signals fired alongside it, and what the engine recommended.

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Pre-filtered to Invalid Hostname Validation (CN/SAN Mismatch). See real IOCs this signal caught and the verdicts the engine returned.
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