ThreatFox: DCRat IOCs

Hunt Hypothesis

This hunt detects adversary activity involving the DCRat remote access tool by identifying specific indicators of compromise such as malicious file hashes and network connections within the Azure Sentinel environment. Proactively hunting for these IOCs is critical to rapidly identify early-stage lateral movement or command-and-control communications, enabling the SOC team to contain potential data exfiltration before it escalates into a broader incident.

IOC Summary

Malware Family: DCRat Total IOCs: 2 IOC Types: ip:port

KQL: Ip Hunt

// Hunt for network connections to known malicious IPs
// Source: ThreatFox - DCRat
let malicious_ips = dynamic(["128.90.108.184", "45.74.6.146"]);
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(["128.90.108.184", "45.74.6.146"]);
DeviceNetworkEvents
| where RemoteIP in (malicious_ips)
| project Timestamp, DeviceName, RemoteIP, RemotePort, InitiatingProcessFileName, ActionType
| order by Timestamp desc

Required Data Sources

References

• ThreatFox — DCRat

False Positive Guidance

Here are specific false positive scenarios and corresponding filters for the ThreatFox: DCRat IOCs detection rule in an enterprise environment:

• Scenario: Legitimate Remote Administration via PowerShell

  • Context: System Administrators frequently use PowerShell to query remote endpoints or push configurations. If a legitimate admin script invokes powershell.exe with arguments containing DCRat-associated hash values (e.g., specific DLLs used by the admin tool) or connects to a known internal IP that matches a DCRat IOC, the rule may trigger.
  • Filter/Exclusion: Exclude events where the parent process is PowerShell.exe running under a domain-admin account (e.g., DOMAIN\svc_admin) and the destination IP falls within the internal corporate subnet range (e.g., 10.x.x.x).

• Scenario: Scheduled Antivirus or EDR Definition Updates

  • Context: Enterprise Endpoint Detection and Response (EDR) agents, such as CrowdStrike Falcon or Microsoft Defender for Endpoint, often download definition updates from vendor cloud services. If the DCRat IOCs include specific certificate thumbprints or file hashes that overlap with the EDR’s update server signatures, scheduled nightly jobs will trigger false alerts.
  • Filter/Exclusion: Create an exclusion based on the process name C:\Program Files\CrowdStrike\FalconSensor\csfalcon.exe (or equivalent for your specific EDR) and filter out events occurring during the defined maintenance window (e.g., 02:00–04:00 local time).

• Scenario: Internal Software Deployment via SCCM/Intune

  • Context: During mass software deployments using Microsoft Endpoint Configuration Manager (SCCM) or Microsoft Intune, the deployment engine may execute a script that references a shared library or installer component.