It refers to a domain that operates with restricted accessibility — its HTTP/HTTPS services are either protected, limited to specific users, or intentionally unreachable from the public internet. Threat actors often configure such domains to prevent discovery by scanners and to only allow requests from whitelisted or infected hosts.
Three questions every analyst asks before acting on this signal.
It refers to a domain that operates with restricted accessibility — its HTTP/HTTPS services are either protected, limited to specific users, or intentionally unreachable from the public internet. Threat actors often configure such domains to prevent discovery by scanners and to only allow requests from whitelisted or infected hosts.
Because legitimate web services are typically accessible over the public internet. Domains that block ordinary HTTP requests, return access errors, or only respond to authenticated clients may indicate malicious infrastructures designed for command-and-control (C2) or data exfiltration. However, some legitimate services such as private APIs or partner networks can show similar behavior.
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.
{
"slug": "unsuccessful_web_request",
"name": "Non-Public Domain",
"group": "http_crawling_history",
"subgroup": "http_availability_stability",
"direction": "malicious",
"evidence": {
"uptime_30d_pct": 99.4,
"status_code_mode": 200,
"intermittent_failures_30d": 2,
"last_unreachable_days_ago": 14
}
}4 other signals share the same subgroup. They detect related behaviors and often co-fire on the same IOC.
It indicates that the base domain’s web service (HTTP/HTTPS) is no longer responding or has gone offline. This behavior …
This term refers to a web service (HTTP/HTTPS) that has been continuously active and reachable for a long duration witho…
It indicates that the domain has recently started serving web content over HTTP or HTTPS after a long period of inactivi…
It refers to a domain whose HTTP or HTTPS service repeatedly switches between being online and offline within short time…
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