ThreatFox: DCRat IOCs

Hunt Hypothesis

This detection rule identifies active DCRat malware infections by matching network and endpoint telemetry against seven specific Indicators of Compromise (IOCs) known to facilitate remote access trojan capabilities. Proactively hunting for these IOCs within Azure Sentinel is critical because DCRat’s ability to establish persistent command-and-control channels allows adversaries to exfiltrate sensitive data before traditional signature-based defenses can react.

IOC Summary

Malware Family: DCRat Total IOCs: 7 IOC Types: sha256_hash, url, md5_hash, ip:port, sha1_hash

KQL: Ip Hunt

// Hunt for network connections to known malicious IPs
// Source: ThreatFox - DCRat
let malicious_ips = dynamic(["91.92.241.38", "102.220.160.231"]);
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(["91.92.241.38", "102.220.160.231"]);
DeviceNetworkEvents
| where RemoteIP in (malicious_ips)
| project Timestamp, DeviceName, RemoteIP, RemotePort, InitiatingProcessFileName, ActionType
| order by Timestamp desc

KQL: Url Hunt

// Hunt for access to known malicious URLs
// Source: ThreatFox - DCRat
let malicious_urls = dynamic(["http://cx288605.tw1.ru/L1nc0In.php"]);
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 - DCRat
let malicious_hashes = dynamic(["92937973d50ddd6bff639bf35feb25b119f56edd", "9fce0558dd8b2061c7a8baf0877d5384", "9b0e3f974dac0023599bb604b5b30e3e763c2d1d28ecff80d307ca73dc06243f"]);
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 — DCRat

False Positive Guidance

Here are 5 specific false positive scenarios for the ThreatFox: DCRat IOCs detection rule, including tailored filters and exclusions suitable for an enterprise environment:

• Scenario: Scheduled Antivirus or EDR Full Scans

  • Context: Enterprise Endpoint Detection and Response (EDR) solutions like CrowdStrike Falcon, Microsoft Defender for Endpoint, or Symantec Endpoint Protection often perform scheduled full scans during off-hours. These agents may generate network traffic to their management consoles that matches DCRat’s C2 communication patterns (specifically specific port usage or certificate thumbprints).
  • Filter/Exclusion: Create a rule exclusion for source IPs belonging to the EDR management cluster and exclude process names containing *FalconSensor.exe, MsMpEng.exe, or Symantec Client*.exe when communicating with known internal EDR gateway ports (e.g., 80, 443, 9601).

• Scenario: Automated Backup Agent Communication

  • Context: Cloud backup agents such as Veeam Backup & Replication, Rubrik, or Commvault frequently establish persistent connections to cloud repositories. If the DCRat IOCs include specific User-Agent strings or TLS fingerprint characteristics common in enterprise backup software, these legitimate backup jobs will trigger alerts during nightly windows.
  • Filter/Exclusion: Exclude traffic where the destination IP is within the organization’s designated “Backup Infrastructure” subnet (e.g., 10.50.x.x) and filter out process names matching VeeamAgent.exe, rubrik-agent, or commcell_service during defined maintenance windows (e.g., 02:00–06:00 local time).

• Scenario: Internal Software Update Services

  • Context: Enterprise patch management tools