ThreatFox: EvilExtractor IOCs

Hunt Hypothesis

This detection rule identifies adversary activity involving the EvilExtractor malware by monitoring for specific indicators of compromise such as malicious file hashes and network connections. Proactively hunting for these IOCs in Azure Sentinel is critical to rapidly detect early-stage ransomware or data exfiltration campaigns before they escalate into widespread incidents across the enterprise environment.

IOC Summary

Malware Family: EvilExtractor Total IOCs: 3 IOC Types: sha1_hash, md5_hash, sha256_hash

KQL: Hash Hunt

// Hunt for files matching known malicious hashes
// Source: ThreatFox - EvilExtractor
let malicious_hashes = dynamic(["63f3064a8023989933b7d294af76cd5a583eeea38aedfa464cd2ea2cf3a4ed73", "bb5cf9a62dab446da7ebb7650213748dc51037b3", "e384e7389a371c96e5d31effce1242ae"]);
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 — EvilExtractor

False Positive Guidance

Here are 4 specific false positive scenarios for the ThreatFox: EvilExtractor IOCs detection rule, including targeted filters and exclusions suitable for an enterprise environment:

• Scenario: Antivirus Definition Updates via Scheduled Tasks

  • Context: Enterprise endpoints running Microsoft Defender Antivirus or Symantec Endpoint Protection often trigger scheduled tasks (e.g., Task Scheduler jobs named “UpdateDefinitions”) that download and extract signature definition files. These extraction processes frequently generate file hashes matching the EvilExtractor IOCs, particularly when extracting compressed definition archives using standard system utilities like 7-Zip or native PowerShell Expand-Archive.
  • Filter/Exclusion: Exclude process paths where the parent process is Task Scheduler (svchost.exe -k netsvcs) and the command line contains keywords related to “definition update” or specific vendor names (e.g., Microsoft, Symantec). Additionally, whitelist the specific file hashes of known definition extractors used by your AV suite.

• Scenario: Software Deployment via Configuration Management Tools

  • Context: IT administrators using Microsoft Endpoint Manager (Intune) or SCCM (System Center Configuration Manager) often deploy software packages that involve extracting .msi or .zip payloads to a temporary directory before installation. The extraction engine utilized by these tools (often leveraging 7z.dll or similar) may match the IOCs associated with EvilExtractor, especially when deploying large application suites like Adobe Creative Cloud or Office 365.
  • Filter/Exclusion: Create a filter to exclude alerts where the initiating process is CcmExec.exe (SCCM) or IntuneManagementExtension.exe, and the execution path resides within standard deployment directories such as C:\Windows\CCM\Cache or `C:\ProgramData\Microsoft\Intune Management Extension