Urausy

Overview

Ransom:Win32/Urausy (also known as a 'Police Trojan') represents a massive, historical wave of screen-locking ransomware. Unlike modern crypto-ransomware that encrypts files, Urausy locks the user's desktop interface entirely (`T1486`) and displays a localized, highly realistic warning purportedly from a local law enforcement agency (like the FBI, Interpol, or local police). The warning claims the user was caught viewing illegal content and must pay a 'fine' (usually via pre-paid cards like Ukash or Paysafecard) to unlock the machine.

Understanding Urausy (Screen-Locking Ransomware)
To an end-user, the computer is completely unusable; upon boot, they are immediately presented with a full-screen police warning that cannot be closed. For a SOC analyst, Urausy is a legacy threat that highlights the evolution of ransomware from psychological extortion (scareware) to actual cryptographic damage.

Execution and Extortion Mechanics
Urausy was primarily distributed via exploit kits (like Blackhole or Fiesta) (`T1189`) injected into compromised websites. Upon successful exploitation, the payload is dropped and executes. It achieves persistence by replacing the default Windows shell (typically `explorer.exe`) in the registry (`HKCU\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\Shell`) with its own executable (`T1547.004`). It actively monitors for and terminates task manager processes (`taskmgr.exe`) to prevent the user from killing the locker (`T1562.001`). Crucially, Urausy uses geolocation (via the victim's IP address) to display a customized ransom note in the correct language, featuring the logos of local law enforcement.

Indicators of Compromise & Impact
The impact is a total denial of access to the desktop environment, though the underlying files are *not* encrypted. Host-based IoCs include the modification of the Winlogon Shell registry key, the presence of the malicious executable in the `%AppData%` directory, and the inability to launch `taskmgr.exe`. Network IoCs involve initial connections to known exploit kit landing pages.

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

Sigma Rule

title: Suspicious Urausy Activity
id: 22e6bd7bd4ad5e7ce6e5f3082fce0b61
status: experimental
description: Detects generic indicators of the urausy malware family.
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains:
            - "*urausy*"
    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 machine into Safe Mode with Command Prompt; this often bypasses the Winlogon Shell hijack.
2. From the command prompt, launch `regedit.exe` and restore the `HKCU\Software\Microsoft\Windows NT\CurrentVersion\Winlogon\Shell` key back to `explorer.exe`.
3. Locate and delete the malicious Urausy executable (often located in `%AppData%` or `%Temp%`).
4. After rebooting normally, run a full AV scan to remove any secondary droppers that arrived with the exploit kit.

What to Avoid

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

1. Do not format the drive or restore from backup immediately; unlike crypto-ransomware, Urausy infections can usually be removed without any data loss.
2. Avoid paying the 'fine'; it goes directly to cybercriminals, not law enforcement.

References & External Analysis

• Search "urausy" on VirusTotal (External Analysis)

Frequently Asked Questions

Related Families (Category: ransomware)

Explore other malware families in the same category:

• Defmid
• Crypton
• Rastabaf
• Murlo
• Seeav

Machine-readable

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