ThreatFox: WannaCryptor IOCs

Hunt Hypothesis

This detection rule identifies WannaCryptor ransomware activity by monitoring for specific IOCs associated with its propagation via phishing or EternalBlue exploits, including unusual network traffic and file encryption events. A proactive hunt is essential in Azure Sentinel to rapidly detect early-stage lateral movement and unpatched system compromises before widespread data encryption occurs across the enterprise environment.

IOC Summary

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

Type	Value	Threat Type	First Seen	Confidence
sha1_hash	`02c8512b8bc8cce7e46a4d28ea46250076edef9c`	payload	2026-08-08	95%
md5_hash	`6da5f33515b187df3620e7463fab9995`	payload	2026-08-08	95%
sha256_hash	`b9cf80a5e63577b018937534f6219eb29876c2163f0cdad7341acc2deef2859f`	payload	2026-08-08	95%
md5_hash	`f0d062c4f07188525d9b14c975e871ed`	payload	2026-08-08	95%
sha1_hash	`8616383a669c0d3ba743bc9f122954257fb28bd9`	payload	2026-08-08	95%
sha256_hash	`e1ee2b7aeeb62f063134d78df6e522afde0952eca1701fb8d0835abe18ef16bc`	payload	2026-08-08	95%

KQL: Hash Hunt

// Hunt for files matching known malicious hashes
// Source: ThreatFox - WannaCryptor
let malicious_hashes = dynamic(["02c8512b8bc8cce7e46a4d28ea46250076edef9c", "6da5f33515b187df3620e7463fab9995", "b9cf80a5e63577b018937534f6219eb29876c2163f0cdad7341acc2deef2859f", "f0d062c4f07188525d9b14c975e871ed", "8616383a669c0d3ba743bc9f122954257fb28bd9", "e1ee2b7aeeb62f063134d78df6e522afde0952eca1701fb8d0835abe18ef16bc"]);
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

False Positive Scenarios: ThreatFox: WannaCryptor IOCs

Scenario 1: Scheduled Antivirus Definition Updates
- Context: Enterprise endpoints running Microsoft Defender for Endpoint or Symantec Endpoint Protection often trigger the rule when downloading large definition update packages. These updates contain executable hashes that may overlap with known WannaCryptor signatures, especially if the update server is hosted on a port commonly used by ransomware (e.g., 445) and involves significant file I/O activity during off-hours.
- Suggested Filter: Exclude traffic originating from the specific IP ranges of the vendor’s update servers (e.g., *.update.microsoft.com or Symantec CDN IPs) where the user agent string contains “AntivirusUpdate” and the process name is MsMpEng.exe or SymantecDefender.exe.
Scenario 2: Automated Backup Jobs via SMB
- Context: Nightly backup routines executed by tools like Veeam Backup & Replication or Rubrik often involve massive file reads and writes over the SMB protocol (Port 445). Since WannaCryptor exploits EternalBlue on Port 445, these legitimate high-volume data transfers can mimic the “unusual network traffic patterns” and “file encryption activity” indicators defined in the detection logic.
- Suggested Filter: Create an exclusion for processes running under specific service accounts (e.g., DOMAIN\BackupService) that initiate connections to known backup repository IPs, provided the destination port is 445 and the source process hash matches the verified signature of the backup agent.
Scenario 3: Patch Management Deployment via WSUS
- Context: During scheduled maintenance windows, Windows Server Update Services (WSUS) or tools like Ivanti Neurons for Patch Management push updates