ThreatFox: WannaCryptor IOCs

Hunt Hypothesis

This detection rule identifies systems exhibiting indicators of compromise linked to the WannaCryptor ransomware, such as specific file hashes and network connections that signal active encryption attempts or lateral movement. Proactively hunting for these IOCs in Azure Sentinel is critical because early identification allows the SOC team to isolate affected endpoints before the ransomware propagates across the environment, thereby minimizing potential data loss and operational downtime.

IOC Summary

Malware Family: WannaCryptor Total IOCs: 6 IOC Types: sha256_hash, sha1_hash, md5_hash

Type	Value	Threat Type	First Seen	Confidence
sha1_hash	`d313053982390ae6a4707aeba20451cfc13fc88e`	payload	2026-08-30	95%
md5_hash	`70f6dff404b94d943db1514648700cfa`	payload	2026-08-30	95%
sha256_hash	`507bbce068c50bc2e2c3907debe65c3bf974ac1c2ace16d15c952bd3a72c15f2`	payload	2026-08-30	95%
md5_hash	`e7905f19dc5cebd37e3f9e2f65368b04`	payload	2026-08-30	95%
sha256_hash	`0960a25a046f08f30489bce5f7cc6e83af9b21989f8e937c57722cafe00b2dca`	payload	2026-08-30	95%
sha1_hash	`12da85ebf11415b0837c4930af8ae1f46194e8cb`	payload	2026-08-30	95%

KQL: Hash Hunt

// Hunt for files matching known malicious hashes
// Source: ThreatFox - WannaCryptor
let malicious_hashes = dynamic(["d313053982390ae6a4707aeba20451cfc13fc88e", "70f6dff404b94d943db1514648700cfa", "507bbce068c50bc2e2c3907debe65c3bf974ac1c2ace16d15c952bd3a72c15f2", "e7905f19dc5cebd37e3f9e2f65368b04", "0960a25a046f08f30489bce5f7cc6e83af9b21989f8e937c57722cafe00b2dca", "12da85ebf11415b0837c4930af8ae1f46194e8cb"]);
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 5 specific false positive scenarios for the ThreatFox: WannaCryptor IOCs detection rule, along with suggested filters and exclusions tailored for an enterprise environment:

Scenario: Enterprise Backup Agent Scanning Encrypted Archives
- Context: The organization uses Veeam Backup & Replication or Commvault. During nightly backup windows, the agent scans large .vbk or .vmtkx files which may contain internal signatures matching WannaCryptor’s encryption patterns (specifically file extensions like .wncry or specific hash values).
- Filter/Exclusion: Create a rule exclusion based on the Process Name (VeeamAgent.exe, commvault_agent.exe) and restrict detection to non-business hours if the backup schedule is fixed. Alternatively, exclude the specific file paths where backups are stored (e.g., \\BackupServer\Shared\).
Scenario: Scheduled Antivirus Definition Updates
- Context: The enterprise deploys Microsoft Defender for Endpoint or Symantec Endpoint Protection. During automated definition updates, the engine extracts and scans new signature databases. These databases often contain binary blobs that trigger the specific IOCs (hashes) associated with WannaCryptor’s encryption module.
- Filter/Exclusion: Exclude processes related to AV update services. For example, filter out events where ProcessName equals MsMpEng.exe or SymantecEngine.exe and the CommandLine contains keywords like “update” or “definition”.
Scenario: Automated Patch Deployment via Configuration Management
- Context: IT operations utilize Microsoft SCCM (Configuration Manager) or Ansible Tower to push Windows updates. The deployment agent creates temporary staging files in %TEMP% directories that mimic the file structure and hash characteristics of WannaCryptor’s ransom