ThreatFox: WannaCryptor IOCs

Hunt Hypothesis

This hypothesis targets the presence of WannaCryptor indicators, which signal an active ransomware infection that encrypts critical data and exploits network vulnerabilities to propagate laterally. Proactively hunting for these IOCs in Azure Sentinel allows the SOC to identify compromised endpoints early, enabling rapid isolation and containment before the malware can spread across the environment and maximize data loss.

IOC Summary

Malware Family: WannaCryptor Total IOCs: 9 IOC Types: sha256_hash, sha1_hash, md5_hash

Type	Value	Threat Type	First Seen	Confidence
md5_hash	`29e5e53c6bc41825bb1ab63d8650f568`	payload	2026-09-12	95%
sha1_hash	`eb0efb4d11885c7897e2cdd7738c645789fab387`	payload	2026-09-12	95%
md5_hash	`c987878904b7808a850a8f300b9656e8`	payload	2026-09-12	95%
sha256_hash	`ccefe9acb00af5bfc11701b390e8e0dac713ab289a516be091a71a3a0a63a9ba`	payload	2026-09-12	95%
sha1_hash	`a4ee13ffe86517e324030bde7bfb83758e8a8bbc`	payload	2026-09-12	95%
md5_hash	`8e9ac32cc675e6150664d9a663c1d403`	payload	2026-09-12	95%
sha256_hash	`e1f4692aef0eb5bfc8b0dd24d6b6df4bcb687429f41047b57b816b116bd29c90`	payload	2026-09-12	95%
sha256_hash	`e36fcabff0eec569fee5d306df5bec8e3ca576f253f064c4a423989a8156e553`	payload	2026-09-12	95%
sha1_hash	`84a7b7fc20160ebeff25b74bba7066723a72b413`	payload	2026-09-12	95%

KQL: Hash Hunt

// Hunt for files matching known malicious hashes
// Source: ThreatFox - WannaCryptor
let malicious_hashes = dynamic(["29e5e53c6bc41825bb1ab63d8650f568", "eb0efb4d11885c7897e2cdd7738c645789fab387", "c987878904b7808a850a8f300b9656e8", "ccefe9acb00af5bfc11701b390e8e0dac713ab289a516be091a71a3a0a63a9ba", "a4ee13ffe86517e324030bde7bfb83758e8a8bbc", "8e9ac32cc675e6150664d9a663c1d403", "e1f4692aef0eb5bfc8b0dd24d6b6df4bcb687429f41047b57b816b116bd29c90", "e36fcabff0eec569fee5d306df5bec8e3ca576f253f064c4a423989a8156e553", "84a7b7fc20160ebeff25b74bba7066723a72b413"]);
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

Scenario: A legacy financial reporting system uses a scheduled PowerShell script to encrypt daily transaction logs with AES-256 before uploading them to a secure archive, mimicking the file encryption behavior of WannaCryptor.
- Filter/Exclusion: Exclude processes where the parent process is powershell.exe or pwsh.exe and the command line contains specific encryption parameters (e.g., -Algorithm AES256 or -Encrypt) while the working directory is within the designated C:\Finance\Reports\ path.
Scenario: An IT administrator manually runs a batch script to encrypt sensitive customer data files using 7z (7-Zip) with a strong password as part of a quarterly data backup rotation, triggering IOCs related to file modification and encryption.
- Filter/Exclusion: Exclude events where the executable is 7z.exe or 7za.exe and the command line includes the -p (password) flag or -he (encrypt headers) option, specifically when the user account belongs to the BackupAdmins group.
Scenario: A software development team uses a CI/CD pipeline agent (e.g., Jenkins or Azure DevOps) that executes a build step to encrypt source code archives using GPG before pushing them to a private registry, which may be misidentified as ransomware activity due to rapid file changes.
- Filter/Exclusion: Exclude processes where the parent process is a known CI/CD agent (e.g., jenkins-agent.exe, vsts-agent.exe) and the command line contains gpg or openssl enc commands, restricted to the C:\BuildAgent\ directory.
Scenario: A security team performs a controlled “game day” or tabletop exercise where they deploy a benign encryption tool (like CrypTool) to simulate a ransom