ThreatFox: Unknown malware IOCs

Hunt Hypothesis

This hunt targets the presence of six specific IOCs linked to unknown malware, which may indicate an active compromise or a stealthy initial access vector that evaded standard signature-based detections. Proactively hunting for these indicators in Azure Sentinel is critical to identify early-stage infections or lateral movement attempts before they escalate into a full-blown breach, ensuring rapid containment in high-severity scenarios.

IOC Summary

Malware Family: Unknown malware Total IOCs: 6 IOC Types: sha256_hash, ip:port, url, domain

KQL: Ip Hunt

// Hunt for network connections to known malicious IPs
// Source: ThreatFox - Unknown malware
let malicious_ips = dynamic(["138.197.31.70", "27.14.2.173"]);
CommonSecurityLog
| where DestinationIP in (malicious_ips) or SourceIP in (malicious_ips)
| project TimeGenerated, SourceIP, DestinationIP, DestinationPort, DeviceAction, Activity
| order by TimeGenerated desc

KQL: Ip Hunt Device

// Hunt in Defender for Endpoint network events
let malicious_ips = dynamic(["138.197.31.70", "27.14.2.173"]);
DeviceNetworkEvents
| where RemoteIP in (malicious_ips)
| project Timestamp, DeviceName, RemoteIP, RemotePort, InitiatingProcessFileName, ActionType
| order by Timestamp desc

KQL: Domain Hunt

// Hunt for DNS queries to known malicious domains
// Source: ThreatFox - Unknown malware
let malicious_domains = dynamic(["foresightfinances.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.raideurs.eu/", "https://www.cedipay.cash/"]);
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(["0a0c931f6a7b4d4d66389dab1c83cb4f7355f627399a040e79ce34ae2ab02957"]);
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 engineer uses curl or wget to download a specific binary or configuration file from a known internal artifact repository (e.g., Artifactory, Nexus) that happens to match one of the 6 IOCs (e.g., a specific SHA256 hash or IP address) due to a temporary staging environment or a shared build node.
  • Filter/Exclusion: Exclude alerts where the source IP is within the internal artifact repository CIDR range (e.g., 10.20.0.0/24) AND the user account belongs to the devops-builders AD group.
• Scenario: An IT administrator performs a manual patch deployment using a script that downloads a specific installer package from a third-party vendor’s CDN (e.g., downloads.vendor.com) which is temporarily registered in the ThreatFox IOC list as an “Unknown” IP or domain due to a recent DNS change or shared hosting infrastructure.
  • Filter/Exclusion: Exclude alerts where the destination domain matches the vendor’s known CDN subdomain (e.g., *.cdn.vendor.com) AND the initiating process is powershell.exe or cmd.exe executed by a service account in the it-admins group.
• Scenario: A security team runs a YARA scan or memory dump analysis using a tool like Volatility or YARA that loads a specific library or plugin from a local path or internal share, which inadvertently matches an IOC (e.g., a specific file path or hash) associated with the “Unknown” malware family.
  • Filter/Exclusion: Exclude alerts where the source path contains the security tool’s installation directory (e.g., C:\Tools\Volatility\ or \\fileserver\security\tools\) AND the user account is in the sec-ops group.