ThreatFox: Unknown malware IOCs

Hunt Hypothesis

This hypothesis targets the presence of seven specific indicators of compromise linked to unknown malware, which may indicate an active or dormant infection within the environment. Proactively hunting for these IOCs in Azure Sentinel is critical to identify and contain potential threats before they escalate, given the high severity and the lack of a defined MITRE technique that could otherwise mask the activity.

IOC Summary

Malware Family: Unknown malware Total IOCs: 7 IOC Types: url, md5_hash, domain, sha256_hash

KQL: Domain Hunt

// Hunt for DNS queries to known malicious domains
// Source: ThreatFox - Unknown malware
let malicious_domains = dynamic(["robinfireman.xyz"]);
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://sites.google.com/view/facturacion2026mx", "https://dipag.com.mx/api/comprobante/index.html"]);
UrlClickEvents
| where Url has_any (malicious_urls)
| project Timestamp, AccountUpn, Url, ActionType, IsClickedThrough
| order by Timestamp desc

KQL: Hash Hunt

// Hunt for files matching known malicious hashes
// Source: ThreatFox - Unknown malware
let malicious_hashes = dynamic(["2001073e86fb819f81ddfbad029f8bccceb6e877df74e24f140e06d29ed9457e", "f6e001270f7197b715a2181b35ebb3ce0b61344d3fcbe7f78d4ade407f0558af", "188c0c633c07dd5eac1d770132450c3a", "124ea0becb2b4885c536884d42f969af"]);
DeviceFileEvents
| where SHA256 in (malicious_hashes) or SHA1 in (malicious_hashes) or MD5 in (malicious_hashes)
| project Timestamp, DeviceName, FileName, FolderPath, SHA256, InitiatingProcessFileName
| order by Timestamp desc

Required Data Sources

References

• ThreatFox — Unknown malware

False Positive Guidance

• Scenario: A DevOps team deploys a new containerized microservice using a custom Docker image that includes a lightweight, unsigned monitoring agent (e.g., a custom build of node_exporter or a proprietary log shipper) which has not yet been added to the threat intelligence feed.

  • Filter/Exclusion: Exclude alerts where the process path matches the specific container image hash or the parent process is dockerd/containerd-shim and the binary resides in the /usr/local/bin or /opt/app/bin directory.

• Scenario: An IT administrator performs a manual patching task on a legacy Windows Server 2012 R2 host, copying a specific version of the 7z.exe archive utility (version 19.00) from a shared network drive (\\fileserver\tools\) to the local C:\Temp folder for extraction, which matches an IOC hash for an older, benign build of 7-Zip.

  • Filter/Exclusion: Exclude alerts where the file path contains C:\Temp\ or C:\Users\<admin>\Downloads\ and the parent process is cmd.exe or powershell.exe initiated by an interactive user session (Logon Type 2 or 10).

• Scenario: A security engineer runs a YARA rule scan using yara.exe against a large dataset in a staging environment; the specific build of YARA used (v4.2.3) has a known false-positive hash match with a generic “Unknown” malware family due to a shared library dependency (libyara.dll) that is statically linked in the executable.

  • Filter/Exclusion: Exclude alerts where the process name is yara.exe and the command line arguments contain -r (recursive scan) or -s (show strings