ThreatFox: Aisuru IOCs

Hunt Hypothesis

This hunt targets adversary activity involving specific Indicators of Compromise (IOCs) linked to the Aisuru threat actor, which may indicate targeted reconnaissance or initial access attempts within the network. Proactively hunting for these IOCs in Azure Sentinel is critical because early detection of Aisuru’s unique signatures allows the SOC team to isolate potential compromises before they escalate into broader lateral movements or data exfiltration events.

IOC Summary

Malware Family: Aisuru Total IOCs: 3 IOC Types: ip:port

KQL: Ip Hunt

// Hunt for network connections to known malicious IPs
// Source: ThreatFox - Aisuru
let malicious_ips = dynamic(["129.212.233.8", "147.182.140.2", "206.189.94.70"]);
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(["129.212.233.8", "147.182.140.2", "206.189.94.70"]);
DeviceNetworkEvents
| where RemoteIP in (malicious_ips)
| project Timestamp, DeviceName, RemoteIP, RemotePort, InitiatingProcessFileName, ActionType
| order by Timestamp desc

Required Data Sources

References

• ThreatFox — Aisuru

False Positive Guidance

Here are 4 specific false positive scenarios for the ThreatFox: Aisuru IOCs detection rule, tailored for a legitimate enterprise environment:

• Scheduled Endpoint Protection Scans by Admin Tools

  • Scenario: The organization’s centralized endpoint management console (e.g., Microsoft Defender for Endpoint or CrowdStrike Falcon) performs daily scheduled scans. During these updates, the scanner downloads and executes signature definition files that may contain embedded hashes matching Aisuru IOCs as part of a broader threat intelligence feed update.
  • Filter/Exclusion: Create an exclusion rule to suppress alerts originating from specific service accounts (e.g., svc-defender-updater) or processes running under the System context on designated management servers, provided the execution path matches the known installation directory of the EDR agent.

• Enterprise Email Gateway Content Filtering

  • Scenario: The corporate email security gateway (e.g., Proofpoint, Mimecast, or Microsoft Defender for Office 365) processes inbound and outbound traffic. It may generate logs indicating a match against Aisuru IOCs when scanning large attachments or URLs within newsletters from legitimate vendors that utilize shared third-party hosting infrastructure known to host Aisuru-related resources.
  • Filter/Exclusion: Exclude alerts where the source IP belongs to the organization’s trusted email gateway subnet and the user agent string identifies a known mail transport service, specifically filtering out events tagged as “Content Scanning” or “URL Rewriting” rather than “User Interaction.”

• Automated Software Deployment via Configuration Management

  • Scenario: During routine patching cycles managed by automation tools like Ansible, Chef, or SCCM (System Center Configuration Manager), deployment agents push updates to workstations. These agents may temporarily download and execute installer packages that include Aisuru IOCs as part of