ThreatFox: Unknown malware IOCs

Hunt Hypothesis

This detection rule identifies potential unknown malware threats by correlating forty distinct Indicators of Compromise (IOCs) that may evade standard signature-based defenses. A proactive hunt is essential in Azure Sentinel to uncover stealthy adversary activities and rapidly isolate compromised assets before they can establish persistence or exfiltrate sensitive data.

IOC Summary

Malware Family: Unknown malware Total IOCs: 40 IOC Types: url, domain

Type	Value	Threat Type	First Seen	Confidence
domain	herault-elagage.fr	payload_delivery	2026-08-17	90%
domain	emasrl.com	payload_delivery	2026-08-17	90%
domain	rochesterphotoboothrentals.com	payload_delivery	2026-08-17	90%
domain	aak.istanbul	payload_delivery	2026-08-17	90%
domain	casinogooroo.com	payload_delivery	2026-08-17	90%
domain	wirthinger.de	payload_delivery	2026-08-17	90%
domain	vb-howto.com	payload_delivery	2026-08-17	90%
domain	wateronlydries.com	payload_delivery	2026-08-17	90%
domain	aprireunlocale.it	payload_delivery	2026-08-17	90%
domain	ditttos.com	payload_delivery	2026-08-17	90%
domain	dzakwan.com	payload_delivery	2026-08-17	90%
domain	jun99.net	payload_delivery	2026-08-17	90%
domain	hopscotchva.com	payload_delivery	2026-08-17	90%
domain	farmaciaseminari.com	payload_delivery	2026-08-17	90%
domain	asquareengineering.com	payload_delivery	2026-08-17	90%
domain	planetwearz.com	payload_delivery	2026-08-17	90%
domain	faceandbodystudio.com	payload_delivery	2026-08-17	90%
domain	clinicadentalcasany.com	payload_delivery	2026-08-17	90%
domain	wulcano.com	payload_delivery	2026-08-17	90%
domain	shaikhsalman.net	payload_delivery	2026-08-17	90%
domain	newyorkcasinohotels.com	payload_delivery	2026-08-17	90%
domain	360-solutions.com.au	payload_delivery	2026-08-17	90%
domain	singaporecasinogames.com	payload_delivery	2026-08-17	90%
domain	prestigeurgentcare.net	payload_delivery	2026-08-17	90%
domain	zonreizen.nl	payload_delivery	2026-08-17	90%

KQL: Domain Hunt

// Hunt for DNS queries to known malicious domains
// Source: ThreatFox - Unknown malware
let malicious_domains = dynamic(["herault-elagage.fr", "emasrl.com", "rochesterphotoboothrentals.com", "aak.istanbul", "casinogooroo.com", "wirthinger.de", "vb-howto.com", "wateronlydries.com", "aprireunlocale.it", "ditttos.com", "dzakwan.com", "jun99.net", "hopscotchva.com", "farmaciaseminari.com", "asquareengineering.com", "planetwearz.com", "faceandbodystudio.com", "clinicadentalcasany.com", "wulcano.com", "shaikhsalman.net", "newyorkcasinohotels.com", "360-solutions.com.au", "singaporecasinogames.com", "prestigeurgentcare.net", "zonreizen.nl", "ope.com.br", "getmagicthimble.com", "gbs-guinee.com", "offerteschilderwerken.be", "carolinajane.net", "phonglong.com", "simple88.net", "glaube.at", "datafruit.biz", "tazebilgi.net", "pixs.jp", "holdenmed.com", "xray-gifts.com"]);
DnsEvents
| where Name has_any (malicious_domains)
| project TimeGenerated, Computer, Name, IPAddresses, QueryType
| order by TimeGenerated desc

KQL: Url Hunt

// Hunt for access to known malicious URLs
// Source: ThreatFox - Unknown malware
let malicious_urls = dynamic(["https://www.talcgrindingmill.com/", "https://gbs-guinee.com/"]);
UrlClickEvents
| where Url has_any (malicious_urls)
| project Timestamp, AccountUpn, Url, ActionType, IsClickedThrough
| order by Timestamp desc

Required Data Sources

Sentinel Table	Notes
DnsEvents	Ensure this data connector is enabled
UrlClickEvents	Ensure this data connector is enabled

References

• ThreatFox — Unknown malware

False Positive Guidance

Here are 5 specific false positive scenarios for the ThreatFox: Unknown malware IOCs rule, including tailored filters and exclusions:

• Scenario: Automated Endpoint Protection Updates

  • Context: The enterprise uses CrowdStrike Falcon or Microsoft Defender for Endpoint. During scheduled maintenance windows (e.g., every Tuesday at 02:00 AM), the endpoint agent performs a full definition update, generating hundreds of new hashes and network connections that match “Unknown” IOCs in the ThreatFox feed before they are whitelisted.
  • Filter/Exclusion: Create an exclusion rule based on the Source Process Name (C:\Program Files\CrowdStrike\csagent.exe or MsMpEng.exe) and restrict detection to non-maintenance hours (e.g., exclude events occurring between 01:00 and 04:00 AM).

• Scenario: DevOps CI/CD Pipeline Artifact Scanning

  • Context: The internal Jenkins or GitLab Runner servers frequently pull new Docker images and build artifacts from public registries (Docker Hub, GitHub Packages) during active development hours. These transient downloads contain unique hashes that have not yet been ingested into the ThreatFox reputation database, triggering a flood of “Unknown” alerts.
  • Filter/Exclusion: Exclude traffic originating from specific Source IP ranges assigned to the CI/CD cluster (e.g., 10.20.45.0/24) and filter out IOCs where the File Type is identified as Docker Image or Container Manifest.

• Scenario: Scheduled Third-Party Backup Jobs

  • Context: The organization runs nightly backups using Veeam Backup & Replication. The backup agents scan large file repositories and create temporary staging files with