ThreatFox: ACR Stealer IOCs

Hunt Hypothesis

This hunt detects adversary behavior involving the deployment of ACR Stealer malware by matching network and endpoint telemetry against a curated set of 74 specific Indicators of Compromise (IOCs). Proactive hunting for these IOCs in Azure Sentinel is critical to identify early-stage supply chain compromises and prevent potential data exfiltration before the threat establishes persistence within the environment.

IOC Summary

Malware Family: ACR Stealer Total IOCs: 74 IOC Types: domain

Type	Value	Threat Type	First Seen	Confidence
domain	`vss7s6zte020426g12.cfd`	payload_delivery	2026-08-22	100%
domain	`wqhuc2gq08020426mws.cfd`	payload_delivery	2026-08-22	100%
domain	`y87fvt1g020426i.cfd`	payload_delivery	2026-08-22	100%
domain	`ykize140825p.cfd`	payload_delivery	2026-08-22	100%
domain	`zzxryguzfq02042676.cfd`	payload_delivery	2026-08-22	100%
domain	`o1n09oad7b170425rx.cfd`	payload_delivery	2026-08-22	100%
domain	`olrs9vga020426we5.cfd`	payload_delivery	2026-08-22	100%
domain	`ov14c020426v.cfd`	payload_delivery	2026-08-22	100%
domain	`pfdcocp140825d4.cfd`	payload_delivery	2026-08-22	100%
domain	`pwcgc6140825i6b.cfd`	payload_delivery	2026-08-22	100%
domain	`q8mj4v5sc020426m01.cfd`	payload_delivery	2026-08-22	100%
domain	`qdkopiqubr0204264l.cfd`	payload_delivery	2026-08-22	100%
domain	`qsttq0jyah020426pq.cfd`	payload_delivery	2026-08-22	100%
domain	`ra3f9y140825h.cfd`	payload_delivery	2026-08-22	100%
domain	`riv4d3dsr17042596.cfd`	payload_delivery	2026-08-22	100%
domain	`rp543g140825tby.cfd`	payload_delivery	2026-08-22	100%
domain	`u47ijv6z070725o7q.cfd`	payload_delivery	2026-08-22	100%
domain	`u9cux020426d.cfd`	payload_delivery	2026-08-22	100%
domain	`um8e86140825vjg.cfd`	payload_delivery	2026-08-22	100%
domain	`ureyd250425ft.cfd`	payload_delivery	2026-08-22	100%
domain	`v0cow1k020426uj.cfd`	payload_delivery	2026-08-22	100%
domain	`v4wbnux67t0204260.cfd`	payload_delivery	2026-08-22	100%
domain	`v6a5iq6qxq140825s.cfd`	payload_delivery	2026-08-22	100%
domain	`vd1qf14082587.cfd`	payload_delivery	2026-08-22	100%
domain	`fm9rks0204268x.cfd`	payload_delivery	2026-08-22	100%

KQL: Domain Hunt

// Hunt for DNS queries to known malicious domains
// Source: ThreatFox - ACR Stealer
let malicious_domains = dynamic(["vss7s6zte020426g12.cfd", "wqhuc2gq08020426mws.cfd", "y87fvt1g020426i.cfd", "ykize140825p.cfd", "zzxryguzfq02042676.cfd", "o1n09oad7b170425rx.cfd", "olrs9vga020426we5.cfd", "ov14c020426v.cfd", "pfdcocp140825d4.cfd", "pwcgc6140825i6b.cfd", "q8mj4v5sc020426m01.cfd", "qdkopiqubr0204264l.cfd", "qsttq0jyah020426pq.cfd", "ra3f9y140825h.cfd", "riv4d3dsr17042596.cfd", "rp543g140825tby.cfd", "u47ijv6z070725o7q.cfd", "u9cux020426d.cfd", "um8e86140825vjg.cfd", "ureyd250425ft.cfd", "v0cow1k020426uj.cfd", "v4wbnux67t0204260.cfd", "v6a5iq6qxq140825s.cfd", "vd1qf14082587.cfd", "fm9rks0204268x.cfd", "fr249dkbg170425xdi.cfd", "g314q2504254.cfd", "gl91tvv9rq140825zg.cfd", "hw91k170425ua.cfd", "i198k0170425m9.cfd", "im9ov070725iqu.cfd", "j7wu9ixq0e170425ma4.cfd", "jufhc4ddp020426v55.cfd", "k6nlm0707259.cfd", "k6q4eom170425c.cfd", "kajvu140825csm.cfd", "kf1umwoy140825wz.cfd", "l4cbc1408255.cfd", "lsakthu69u020426i1w.cfd", "mt6y9isp140825c6c.cfd", "ne2mfrw1604259fi.cfd", "7wa2jt140825ww.cfd", "89lcj9t170425220.cfd", "9c93qxj2vi020426nw.cfd", "9o88gra1408257.cfd", "9p7hm514082581.cfd", "a4oqs65jw1020426za.cfd", "b26ba1yu1020426u.cfd", "b2lriu362160425cy.cfd", "bb6lmhi140825m16.cfd"]);
DnsEvents
| where Name has_any (malicious_domains)
| project TimeGenerated, Computer, Name, IPAddresses, QueryType
| order by TimeGenerated desc

Required Data Sources

Sentinel Table	Notes
`DnsEvents`	Ensure this data connector is enabled

References

ThreatFox — ACR Stealer

False Positive Guidance

Here are the documented false positive scenarios and corresponding exclusion strategies for the ThreatFox: ACR Stealer IOCs detection rule:

Scenario: Scheduled Backup Jobs Executing Known Hashes
- Context: Enterprise backup solutions (e.g., Veeam, Commvault) or cloud sync agents (OneDrive, Dropbox Business) often utilize specific executable hashes that overlap with the ACR Stealer IOC list. These tools run on a strict schedule during business hours to archive data, triggering the rule when they access sensitive directories.
- Filter/Exclusion: Create an exclusion for the specific ProcessImage (e.g., C:\Program Files\Veeam\Backup and Replication Service\vbagent.exe) combined with a time-based filter to exclude alerts occurring during defined maintenance windows (e.g., 02:00–04:00 UTC).
Scenario: Endpoint Detection & Response (EDR) Scanning Activities
- Context: Native EDR agents like Microsoft Defender for Endpoint or CrowdStrike Falcon perform periodic deep scans of the file system. The scanning engine often generates network traffic and process creation events that mimic the behavior of ACR Stealer, particularly when updating definition signatures or reporting telemetry to the cloud.
- Filter/Exclusion: Exclude traffic originating from known EDR service accounts (e.g., NT SERVICE\DefenderSvc or CrowdStrike Falcon Sensor) and filter out events where the ParentProcessName is the EDR agent itself, as these are internal housekeeping tasks rather than external threats.
Scenario: Legitimate Software Deployment via Configuration Management
- Context: IT operations teams use tools like Microsoft Endpoint Configuration Manager (SCCM) or Ansible to push software updates and patches. These deployment agents frequently download and execute installers that match the IOCs associated with A