ThreatFox: DCRat IOCs

Hunt Hypothesis

This hunt hypothesis targets adversaries leveraging the DCRat Remote Access Trojan to establish persistent command execution capabilities and facilitate sensitive data exfiltration within the network. Proactively hunting for these specific IOCs in Azure Sentinel is critical to detect early-stage lateral movement and prevent unauthorized remote control before attackers can fully compromise internal systems.

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(["46.246.12.2", "217.154.183.251"]);
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(["46.246.12.2", "217.154.183.251"]);
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 3-5 specific false positive scenarios for the ThreatFox: DCRat IOCs detection rule, along with suggested filters or exclusions tailored for an enterprise environment:

• Scenario: Automated Patch Management via SCCM/WSUS

  • Context: The System Center Configuration Manager (SCCM) or Windows Update Server (WSUS) frequently pushes updates and executes remote commands to client machines. These processes often spawn wuauserv.exe or ccmexec.exe which initiate network connections and command executions that mimic DCRat’s behavior of executing remote commands and maintaining persistence.
  • Suggested Filter/Exclusion: Exclude traffic where the parent process is ccmexec.exe, wuauclt.exe, or usoc_dla.exe originating from known internal IP ranges (e.g., 10.x.x.x) associated with the patch management infrastructure. Additionally, filter out connections to Microsoft Update endpoints (*.update.microsoft.com) that match the specific IOCs flagged by DCRat.

• Scenario: Remote Desktop Services (RDS) and Terminal Services

  • Context: In environments utilizing Windows Server RDS or Azure Virtual Desktops, administrators frequently use mstsc.exe to connect to remote sessions. The underlying service (TermService) often establishes persistent connections and executes commands within the user session context, which can trigger DCRat’s “remote access” and “command execution” signatures.
  • Suggested Filter/Exclusion: Create an exclusion rule for processes where the executable path contains \System32\rdshost.exe or mstsc.exe. Furthermore, exclude alerts generated during standard business hours (e.g., 08:00–18:00) on known RDS host servers where high-volume remote access is expected.

• **Scenario: Scheduled Backup Jobs