TrojanDownloader:Win32/ICLoader is a highly evasive, specialized payload dropper heavily utilized by initial access brokers to secure a foothold and deploy advanced threats like ransomware or banking trojans.
What is ICLoader?
For general users, ICLoader provides zero visual indicators of infection. For SOC analysts, an ICLoader detection is a critical alert. It is a 'first-stage' threat designed purely to bypass initial security controls, profile the endpoint's defenses, and securely retrieve the final, destructive payload from a remote Command-and-Control (C2) server.
Infection Vectors & Threat Hunting
ICLoader is frequently distributed via weaponized macros in phishing emails or dropped by exploit kits (such as RIG). Upon execution, the loader performs extensive anti-analysis checks, querying the registry and running processes to detect virtual machines, sandboxes, or specific EDR agents. If the environment appears clean, ICLoader connects to its C2 (often utilizing compromised WordPress sites or cloud hosting providers) to download an encrypted binary blob. It decrypts this payload in memory and executes it using Process Hollowing, ensuring the final malware never touches the disk.
Forensic Analysis & Impact
The impact of ICLoader depends entirely on the secondary payload, which is often high-severity ransomware. Incident responders should hunt for EDR alerts related to 'Suspicious Process Injection' or 'Anomalous Child Process Spawning'. Memory forensics is absolutely vital; analysts must capture a RAM image to extract the decrypted secondary payload from the hollowed process. Network analysis will reveal encrypted HTTPS traffic to obscure domains immediately following the initial execution.
Observed techniques used by this family, mapped to the MITRE ATT&CK framework:
| Technique | Name | Tactic |
|---|---|---|
T1105 | Ingress Tool Transfer | Command and Control |
T1055.012 | Process Injection: Process Hollowing | Defense Evasion |
T1497.001 | Virtualization/Sandbox Evasion: System Checks | Defense Evasion |
T1566.001 | Phishing: Spearphishing Attachment | Initial Access |
T1027 | Obfuscated Files or Information | Defense Evasion |
These YARA and Sigma rules are auto-generated based on the family name and aliases. They must be heavily tuned before deployment in a production environment.
rule MALWARE_WIN_ICLOADER {
meta:
description = "Detects Icloader (pua)"
author = "SystemHelpdesk Boilerplate Generator"
date = "2026-07-06"
strings:
$s1 = "icloader" ascii wide nocase
condition:
uint16(0) == 0x5a4d and any of them
}title: Suspicious Icloader Activity
id: fb870f9a71b06e95cd400f5462f8bed5
status: experimental
description: Detects generic indicators of the icloader malware family.
logsource:
category: process_creation
product: windows
detection:
selection:
Image|endswith:
- '\cmd.exe'
- '\powershell.exe'
CommandLine|contains:
- "*icloader*"
condition: selection
level: mediumOrdered checklist for responders. Adapt to your environment and engage professional support for active incidents.
Common mistakes during response to this family that can destroy evidence, spread the infection, or worsen recovery.
Explore other malware families in the same category:
Get this profile as JSON: https://jordanricky1604-ship-it.github.io/malware-families-catalog/api/icloader.json
This profile is part of the Malware Families Catalog, a public dataset of 2,899 malware families. The catalog is also published across our ecosystem: Hugging Face, Kaggle, Replit, StackBlitz, CodeSandbox, and CodePen.