ThreatFox: WannaCryptor IOCs

Hunt Hypothesis

This hunt hypothesis targets adversary behavior where WannaCryptor ransomware executes known indicators of compromise to encrypt critical data and disrupt operations within the environment. Proactively hunting for these specific IOCs in Azure Sentinel is essential to enable early detection before widespread encryption occurs, thereby minimizing downtime and accelerating incident response times.

IOC Summary

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

Type	Value	Threat Type	First Seen	Confidence
sha1_hash	`57ccec59ebeb2aecbc045d01853412ca2b1c3e0e`	payload	2026-07-10	95%
md5_hash	`dc614bc8781cb85e4ddf2bbb7860cb84`	payload	2026-07-10	95%
sha256_hash	`e4846ec6171f65e96c2909ad93359451551e3ac95aa89ab349d5ab773cbaa0d6`	payload	2026-07-10	95%

KQL: Hash Hunt

// Hunt for files matching known malicious hashes
// Source: ThreatFox - WannaCryptor
let malicious_hashes = dynamic(["57ccec59ebeb2aecbc045d01853412ca2b1c3e0e", "dc614bc8781cb85e4ddf2bbb7860cb84", "e4846ec6171f65e96c2909ad93359451551e3ac95aa89ab349d5ab773cbaa0d6"]);
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 in an enterprise environment, along with suggested filters or exclusions:

Endpoint Protection Scanning of Legacy Archives
- Scenario: The organization’s EDR agent (e.g., CrowdStrike Falcon or Microsoft Defender for Endpoint) performs a scheduled deep scan on the C:\Archive\Legacy_Projects directory. This directory contains thousands of archived .zip and .tar files from 2017 that include legitimate copies of the original WannaCryptor ransomware samples used by the security team for training and signature validation. The EDR engine flags these known benign sample files as active IOCs during the scan.
- Suggested Filter: Create an exclusion rule in the EDR console to ignore IOC matches within specific legacy archive paths (e.g., *\Legacy_Projects\*) or exclude file hashes that are marked as “Known Good” in the internal threat intelligence feed.
IT Operations: Automated Patch Deployment via SCCM
- Scenario: The IT Operations team runs a weekly scheduled job using Microsoft System Center Configuration Manager (SCCM) to deploy Windows updates and security patches. As part of this deployment, a script extracts temporary installation packages into C:\Windows\CCMCache which includes the WannaCryptor remediation tool (WannaCryptorFix.exe) used by the vendor. The detection logic triggers when the SCCM service account executes these files, mistaking the legitimate patching activity for an active infection attempt.
- Suggested Filter: Exclude network traffic and file execution events originating from the specific SCCM Service Account (e.g., NT SERVICE\ccmexec or a dedicated svc-scmm-deploy identity) when accessing the C:\Windows\CCMCache directory.