Wintrim

Overview

Trojan:Win32/Wintrim is a persistent, stealthy trojan often functioning as an adware clicker or a backdoor designed to breach endpoint defenses and securely deliver secondary payloads. It is known to heavily inject intrusive advertisements or silently click on hidden ads to generate fraudulent revenue for the attackers.

Understanding Wintrim
To an end-user, a Wintrim infection is typically noticed through severe system sluggishness, unexpected pop-up windows appearing even when browsers are closed, or redirected web searches. For threat intelligence analysts, Wintrim represents a significant nuisance and a potential staging mechanism for further infections, as adware botnets are frequently rented out to distribute more severe malware.

Execution and Evasion Strategies
Wintrim is commonly distributed via massive malspam campaigns containing weaponized attachments, software bundles (`T1189`), or through exploit kits. Upon execution, it utilizes packing to evade static antivirus signatures. It drops a randomized executable into the `%Temp%` or `%AppData%` directory. It establishes persistence by creating a hidden scheduled task or modifying the Registry Run keys. Wintrim frequently injects its ad-clicking or downloading routine into legitimate system processes (like `explorer.exe` or `svchost.exe`) (`T1055`) to mask its outbound network traffic and hide its activity from the user.

Indicators of Compromise (IoCs)
Threat hunters should investigate EDR alerts related to 'Suspicious Process Injection' or 'Anomalous Child Process Spawning'. Network logs will often reveal Wintrim reaching out to known advertising networks or compromised domains using encrypted HTTPS traffic, often generating massive amounts of automated clicks. The presence of unexpected, hidden scheduled tasks designed to execute randomly named binaries in the user's profile is a strong IoC.

MITRE ATT&CK Techniques

Observed techniques used by this family, mapped to the MITRE ATT&CK framework:

Tactical Mitigations

Based on the techniques used by this family, consider the following defensive strategies:

• T1105: Implement network intrusion detection systems (NIDS) and host-based firewalls to block unauthorized inbound or outbound file transfers.

Generated Detections (Boilerplate)

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.

YARA Rule

rule MALWARE_WIN_WINTRIM {
    meta:
        description = "Detects Wintrim (trojan)"
        author = "SystemHelpdesk Boilerplate Generator"
        date = "2026-07-06"
    strings:
        $s1 = "wintrim" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

Sigma Rule

title: Suspicious Wintrim Activity
id: 378c9e70f1f152a6306b15f363869443
status: experimental
description: Detects generic indicators of the wintrim malware family.
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains:
            - "*wintrim*"
    condition: selection
level: medium

Containment & Response Steps

Ordered checklist for responders. Adapt to your environment and engage professional support for active incidents.

1. Isolate the endpoint immediately to prevent Wintrim from generating ad fraud traffic or downloading secondary payloads.
2. Audit the Windows Task Scheduler and Registry Run keys to identify and remove the Wintrim persistence mechanisms.
3. Review firewall and proxy logs to identify the C2 or ad-network domains Wintrim attempted to contact, and block them enterprise-wide.
4. Run a comprehensive anti-malware and adware removal scan to ensure all injected components are removed from the system.

What to Avoid

Common mistakes during response to this family that can destroy evidence, spread the infection, or worsen recovery.

1. Do not close an incident simply because the initial Wintrim dropper was quarantined; always verify if secondary payloads were downloaded.
2. Avoid relying solely on manual file deletion, as the injected processes will likely just recreate the dropped binaries.

References & External Analysis

• Search "wintrim" on VirusTotal (External Analysis)

Frequently Asked Questions

Related Families (Category: trojan)

Explore other malware families in the same category:

• Rockrat
• Moonpie
• Retefe
• Cridex
• Cuegoe

Machine-readable

Get this profile as JSON: https://jordan123234-malware-families-explorer.static.hf.space/api/wintrim.json

Ecosystem & Interactive Environments

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, Zenodo, Replit, StackBlitz, CodeSandbox, and CodePen.