ThreatFox: VShell IOCs

Hunt Hypothesis

This detection identifies adversary activity involving known indicators of compromise from the VShell threat intelligence feed, signaling potential reconnaissance or initial access attempts within the Azure environment. Proactively hunting for these specific IOCs allows the SOC team to rapidly validate and contain emerging threats before they escalate into broader incidents across their Sentinel infrastructure.

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(["49.232.108.35", "89.125.244.131"]);
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(["49.232.108.35", "89.125.244.131"]);
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 the false positive scenarios and corresponding filters for the ThreatFox: VShell IOCs detection rule:

• Scenario: Automated Endpoint Protection Scanning

  • Context: Enterprise EDR agents (e.g., CrowdStrike Falcon, Microsoft Defender for Endpoint) frequently download threat intelligence feeds or definition updates from VShell repositories during scheduled maintenance windows. This triggers the IOCs as a legitimate network connection rather than a malicious beacon.
  • Filter/Exclusion: Exclude traffic originating from known EDR service accounts (e.g., SYSTEM, LocalService) on specific host groups where the EDR is installed, or filter by destination port 443 if the VShell feed update is strictly HTTPS-based.

• Scenario: IT Admin Manual Investigation

  • Context: Security analysts or system administrators manually query the VShell portal via a web browser (e.g., Chrome, Edge) to investigate specific malware signatures or review threat reports. This generates HTTP/HTTPS sessions matching the rule’s IOCs.
  • Filter/Exclusion: Create an exclusion for user accounts belonging to the “SOC_Team” or “IT_Ops” distribution groups, ensuring that interactive logon sessions (Logon Type 2) from these users do not trigger alerts.

• Scenario: Scheduled Backup and Reporting Jobs

  • Context: Automated backup solutions (e.g., Veeam, Commvault) or reporting tools configured to pull metadata from the VShell API run on a daily cron schedule. These background services initiate connections that mimic threat intelligence polling.
  • Filter/Exclusion: Implement a time-based exclusion for the specific scheduled job window (e.g., 02:00–04:00 UTC) and restrict the rule to exclude processes with known executable hashes or names like VeeamBRService.exe or `CommServe