ThreatFox: VShell IOCs

Hunt Hypothesis

This detection rule identifies adversary activity involving specific Indicators of Compromise (IOCs) linked to the VShell malware, which is known for establishing persistent backdoors and facilitating lateral movement within compromised networks. Proactively hunting for these IOCs in Azure Sentinel allows the SOC team to rapidly detect early-stage infections and isolate affected assets before attackers can exploit the established foothold to exfiltrate sensitive data or escalate privileges.

IOC Summary

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

KQL: Ip Hunt

// Hunt for network connections to known malicious IPs
// Source: ThreatFox - VShell
let malicious_ips = dynamic(["43.156.179.8", "64.23.233.95"]);
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(["43.156.179.8", "64.23.233.95"]);
DeviceNetworkEvents
| where RemoteIP in (malicious_ips)
| project Timestamp, DeviceName, RemoteIP, RemotePort, InitiatingProcessFileName, ActionType
| order by Timestamp desc

Required Data Sources

References

• ThreatFox — VShell

False Positive Guidance

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

• Scenario: Automated Security Scanning by EDR Agents

  • Context: Enterprise Endpoint Detection and Response (EDR) platforms like CrowdStrike Falcon, Microsoft Defender for Endpoint, or SentinelOne frequently perform background network sweeps. These agents often query external threat intelligence feeds or update their local IOC databases, triggering connections to VShell infrastructure (which may host threat intel data).
  • Filter/Exclusion: Create a filter to exclude traffic originating from the specific service accounts of your EDR solution (e.g., SourceUser = "FALCON-AGENT-SVC" or ProcessName = "C:\Program Files\CrowdStrike\fsqa.exe") when communicating with VShell IP ranges.

• Scenario: Scheduled Threat Intelligence Feed Ingestion

  • Context: The Security Operations Center (SOC) utilizes a dedicated threat intelligence platform like Tenable.io, Recorded Future, or Anomali ThreatStream. These systems run scheduled jobs (e.g., via PowerShell scripts or Ansible Tower) every 4 hours to pull the latest VShell IOC lists for correlation.
  • Filter/Exclusion: Implement a time-based exclusion window (e.g., 02:00 - 06:00 UTC) combined with a source host filter targeting the specific IP address of your Threat Intelligence ingestion server (e.g., SourceIP = "10.50.4.12").

• Scenario: Admin-Initiated Manual Forensic Queries

  • Context: During routine investigations or quarterly compliance audits, security analysts manually query the VShell portal via their workstations using tools like Splunk Enterprise, **QRadar