ThreatFox: stealler IOCs

Hunt Hypothesis

This hypothesis posits that adversaries are actively deploying Stealer malware to exfiltrate sensitive credentials and financial data through known Indicators of Compromise (IOCs). Proactive hunting for these specific IOCs within Azure Sentinel is critical to rapidly identify early-stage infections before they escalate into widespread data breaches or ransomware incidents.

IOC Summary

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

Type	Value	Threat Type	First Seen	Confidence
md5_hash	`be24a7ff3d55f1b0b790dbec25fb1695`	payload	2026-07-10	95%
sha256_hash	`414d268d7f08654ce40f25c564ac3ac4b624007eb73c09a10e4bb2ff734d6295`	payload	2026-07-10	95%
sha1_hash	`2d0b2c22db90bced28ac61e4a32a185859c5ae86`	payload	2026-07-10	95%

KQL: Hash Hunt

// Hunt for files matching known malicious hashes
// Source: ThreatFox - stealler
let malicious_hashes = dynamic(["be24a7ff3d55f1b0b790dbec25fb1695", "414d268d7f08654ce40f25c564ac3ac4b624007eb73c09a10e4bb2ff734d6295", "2d0b2c22db90bced28ac61e4a32a185859c5ae86"]);
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 — stealler

False Positive Guidance

Here are four specific false positive scenarios for the ThreatFox: Stealler IOCs detection rule in an enterprise environment, along with recommended filters or exclusions:

Endpoint Security Policy Updates via GPO
- Scenario: A scheduled Group Policy Object (GPO) refresh on domain-joined workstations triggers a background update for the organization’s EDR agent (e.g., CrowdStrike Falcon or Microsoft Defender). The update process downloads and executes a signed installer that matches one of the Stealler IOCs because the Stealer malware often mimics legitimate software update behaviors.
- Filter/Exclusion: Exclude processes where the parent process is gpupdate.exe or ccmexec.exe (System Center Configuration Manager) AND the file hash matches a known internal artifact list maintained by the IT Asset Management team.
Third-Party Remote Support Sessions
- Scenario: An IT Helpdesk technician initiates a remote support session using tools like TeamViewer, AnyDesk, or Splashtop. During the initial handshake, these tools spawn helper processes to establish secure tunnels and capture screen data. If the Stealler IOCs include common DLLs or executable names used by these vendors (e.g., tvnserver.exe or specific network driver components), legitimate support tickets will trigger alerts.
- Filter/Exclusion: Create an exclusion rule for processes launched from known “Remote Support” application paths (e.g., C:\Program Files\TeamViewer\) where the user context is a member of the IT_Support or Helpdesk_Admins security group.
Automated Patch Management Jobs
- Scenario: A nightly scheduled job using WSUS (Windows Server Update Services) or Ansible pushes critical patches to a cluster of application servers. The deployment script executes a temporary installer that downloads