ThreatFox: Unknown malware IOCs

Hunt Hypothesis

The ThreatFox: Unknown malware IOCs rule detects potential adversary activity involving unknown malicious indicators that could signal the presence of previously unseen malware in the environment. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate emerging threats before they cause significant damage.

IOC Summary

Malware Family: Unknown malware Total IOCs: 4 IOC Types: domain, ip:port

KQL: Ip Hunt

// Hunt for network connections to known malicious IPs
// Source: ThreatFox - Unknown malware
let malicious_ips = dynamic(["201.71.24.73"]);
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(["201.71.24.73"]);
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(["perfectcloudgate.com", "powerfullcloudflare.com", "powerfireguard.com"]);
DnsEvents
| where Name has_any (malicious_domains)
| project TimeGenerated, Computer, Name, IPAddresses, QueryType
| order by TimeGenerated desc

Required Data Sources

References

• ThreatFox — Unknown malware

False Positive Guidance

• Scenario: A system administrator is using PowerShell to run a scheduled job that downloads a legitimate update from a known Microsoft server.
  Filter/Exclusion: Exclude all PowerShell scripts that originate from https://download.microsoft.com and are associated with known update packages.

• Scenario: A DevOps engineer is executing a CI/CD pipeline using Jenkins that pulls code from a private Git repository.
  Filter/Exclusion: Exclude all Git operations that originate from internal repositories and are executed by Jenkins agents with restricted access.

• Scenario: A database administrator is using SQL Server Management Studio (SSMS) to run a backup job that connects to a remote SQL Server instance.
  Filter/Exclusion: Exclude all outbound connections to SQL Server instances that are whitelisted in the enterprise’s network security policy.

• Scenario: A security analyst is performing a log analysis using ELK Stack (Elasticsearch, Logstash, Kibana) and is querying logs from a centralized logging server.
  Filter/Exclusion: Exclude all log collection activities from the ELK Stack and internal logging servers that are part of the enterprise’s SIEM infrastructure.

• Scenario: A system administrator is using Ansible to deploy configuration changes across multiple servers, which involves copying files from a local repository.
  Filter/Exclusion: Exclude all Ansible playbook executions that originate from internal repositories and are signed with trusted SSH keys.