Onescan

Overview

Rogue:Win32/Onescan is a family of Rogue Antivirus (Scareware) programs designed to extort money from users through fear and deception. It mimics the appearance and behavior of legitimate security software, performing fake system 'scans' and displaying alarming, fabricated alerts regarding critical malware infections. It then demands that the user purchase a 'full license' to remove the non-existent threats.

Understanding Onescan (Scareware)
To an end-user, Onescan is terrifying. It frequently locks the desktop, prevents other programs from running, and bombards the screen with flashing red warnings about critical data loss or impending system failure. For a security analyst, Onescan is a Potentially Unwanted Program (PUP) that utilizes aggressive social engineering (`T1566.002`) and system hijacking (`T1562.001`) to commit fraud.

Execution and Hijacking Mechanics
Onescan is typically distributed via Drive-by Compromise (`T1189`), deceptive advertisements, or bundled with free software. Upon execution, it modifies the Windows Registry (`T1112`) to ensure it runs automatically on startup (`T1547.001`). Crucially, it attempts to Impair Defenses (`T1562.001`) by terminating legitimate antivirus processes, disabling the Windows Task Manager, and sometimes modifying the `hosts` file to block access to legitimate security vendor websites, ensuring the user cannot seek outside help.

Indicators of Compromise & Impact
The primary impact is financial loss for the victim and severe disruption of system usability. Host-based IoCs include the presence of unexpectedly installed software with generic security names (e.g., 'Antivirus Pro 2012', 'System Defender'), anomalous Registry modifications disabling the Task Manager or Registry Editor, and EDR alerts for a process attempting to terminate known security agent services.

MITRE ATT&CK Techniques

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

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_ONESCAN {
    meta:
        description = "Detects Onescan (advanced_threat)"
        author = "SystemHelpdesk Boilerplate Generator"
        date = "2026-07-06"
    strings:
        $s1 = "onescan" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

Sigma Rule

title: Suspicious Onescan Activity
id: c3ca81553e41be30f233958e0f78a114
status: experimental
description: Detects generic indicators of the onescan malware family.
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains:
            - "*onescan*"
    condition: selection
level: medium

Containment & Response Steps

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

1. Boot the infected system into Safe Mode with Networking to bypass the Rogue AV's auto-start mechanisms and regaining access to the desktop.
2. Use a reputable, standalone antimalware scanner (run from a USB drive if necessary) to detect and remove the Onescan executables.
3. Restore the Windows Registry settings, specifically re-enabling the Task Manager and Registry Editor.
4. Check the `hosts` file (`C:\Windows\System32\drivers\etc\hosts`) and remove any malicious entries blocking access to security vendors.

What to Avoid

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

1. Do not enter any credit card information or attempt to 'purchase' the software; it will not fix the computer and the financial data will be stolen.
2. Avoid assuming a simple uninstall will work; Rogue AVs often aggressively defend their files and registry keys.

References & External Analysis

• Search "onescan" on VirusTotal (External Analysis)

Frequently Asked Questions

Related Families (Category: advanced_threat)

Explore other malware families in the same category:

• Monitortool
• Unigo
• Ohmytabs
• Silentall
• Allstars

Machine-readable

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