ThreatFox: WannaCryptor IOCs

Hunt Hypothesis

This hunt targets adversary behavior consistent with the WannaCryptor ransomware campaign by identifying systems interacting with three specific Indicators of Compromise (IOCs) known to facilitate initial infection and lateral movement. Proactive hunting for these IOCs within Azure Sentinel is critical to detect early-stage compromises before encryption begins, allowing the SOC team to isolate affected assets and prevent widespread data loss across the organization.

IOC Summary

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

Type	Value	Threat Type	First Seen	Confidence
sha256_hash	`f2cd38b6c081535971bc76d9aa3560ce3bf33e02986a430464a75e3261c4a8f1`	payload	2026-06-27	95%
sha1_hash	`cc0ae92edb66b42397a1f91894c0e14d12c83454`	payload	2026-06-27	95%
md5_hash	`c0b5ba4fbb2d486362d4be79caecc2b9`	payload	2026-06-27	95%

KQL: Hash Hunt

// Hunt for files matching known malicious hashes
// Source: ThreatFox - WannaCryptor
let malicious_hashes = dynamic(["f2cd38b6c081535971bc76d9aa3560ce3bf33e02986a430464a75e3261c4a8f1", "cc0ae92edb66b42397a1f91894c0e14d12c83454", "c0b5ba4fbb2d486362d4be79caecc2b9"]);
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

Sentinel Table	Notes
`DeviceFileEvents`	Ensure this data connector is enabled

References

ThreatFox — WannaCryptor

False Positive Guidance

Here are specific false positive scenarios for the ThreatFox: WannaCryptor IOCs detection rule, tailored for an enterprise environment:

Enterprise Antivirus Definition Updates
- Scenario: The organization’s endpoint protection platform (e.g., CrowdStrike Falcon or Microsoft Defender for Endpoint) performs a scheduled daily update of its virus definition database. This process often downloads and extracts large signature files that match the WannaCryptor hash IOCs, specifically when the vendor includes a historical “WannaCry” remediation pack in their general update cycle.
- Filter/Exclusion: Create an exclusion rule for the specific service account (e.g., svc-antivirus-updater) and the known process paths of the antivirus engine (e.g., C:\Program Files\CrowdStrike\csagent.exe or MsMpEng.exe). Additionally, filter out events occurring strictly between 02:00 and 04:00 UTC on weekdays.
Patch Management Deployment via SCCM/Intune
- Scenario: The IT Operations team executes a monthly patch deployment using Microsoft Endpoint Configuration Manager (MECM) or Intune to install the cumulative Windows Update that includes the MS17-010 security bulletin (the original WannaCry fix). During this installation, the deployment agent extracts temporary files and scripts containing IOCs associated with the WannaCryptor ransomware family to verify patch integrity before applying.
- Filter/Exclusion: Exclude file creation events originating from the System user context running under the ccmexec.exe (Configuration Manager) or Microsoft.Windows.UpdateOrchestrator process. Whitelist the specific file paths within the Software Distribution point folders (e.g., C:\SMS_CCM\Inbox\Updates).
Scheduled Data Backup and Deduplication Jobs
- Scenario: