Ransim

Category: ransomware · Aliases: HackTool.RanSim, Riskware.RansomwareSimulator, Win32/RanSim · Sample count (EMBER 2018): 1 · Enrichment: insufficient_information · Updated: 2026-07-02T07:08:57Z

Category: RansomwareActor: Unknown / CybercriminalIndustry: Global / OpportunisticMotivation: Opportunistic

Overview

Executive Summary

RanSim (Ransomware Simulator) is technically a benign security testing tool designed by KnowBe4 to simulate ransomware behavior on endpoints. However, because its core function is to mimic the rapid file-encryption behaviors of actual ransomware (to test if local AV/EDR solutions can block it), it is frequently flagged by security software as "HackTool" or generic ransomware. While the tool itself is not malicious, its presence must be carefully contextualized.

Infection Vector and Technical Capabilities

RanSim is not "infectious." It must be intentionally downloaded and executed by a user, typically a system administrator or security analyst running a controlled test. Upon execution, RanSim simulates various ransomware tactics:

Behavioral Mimicry: The tool executes several distinct scenarios, mimicking the specific file iteration and encryption patterns of notorious ransomware families (like Cryptolocker, Locky, or WannaCry) on a set of dummy test files.
No True Encryption: Crucially, RanSim only "encrypts" temporary test files it creates in a specific directory. It does not touch legitimate user data or system files.
Evasion Testing: It tests whether the installed endpoint protection relies solely on static signatures or if it can successfully detect and block anomalous, rapid encryption behavior (heuristics).

Threat Assessment

RanSim itself poses zero threat to data availability or confidentiality. The "threat" is operational: if deployed widely without notifying the Security Operations Center (SOC), the simulated encryption behaviors can trigger massive cascades of high-severity alerts, causing panic and wasting incident response resources.

Incident Response and Remediation

Contextual Verification: If a RanSim alert triggers, immediately verify if an authorized security test or audit is currently underway. Check the path of the executable (usually explicitly named KnowBe4 RanSim).
Safe Handling: If the tool was downloaded by an unauthorized user (e.g., a curious employee), simply delete the executable. No complex remediation or re-imaging is required.
Whitelist Configuration: If RanSim is used for regular testing, coordinate with the SOC to temporarily whitelist the tool's specific hash or execution path to prevent alert fatigue.

Known aliases

Threat reports may refer to this family under multiple names:

MITRE ATT&CK Techniques

This family has been observed using the following ATT&CK techniques: T1486

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_RANSIM {
    meta:
        description = "Detects Ransim (ransomware)"
        author = "SystemHelpdesk Boilerplate Generator"
        date = "2026-07-06"
    strings:
        $s1 = "ransim" ascii wide nocase
        $s2 = "hacktool.ransim" ascii wide nocase
        $s3 = "riskware.ransomwaresimulator" ascii wide nocase
        $s4 = "win32/ransim" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

Sigma Rule

title: Suspicious Ransim Activity
id: fc043fde143713a5eaded7e12050e4a6
status: experimental
description: Detects generic indicators of the ransim malware family.
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains:
            - "*ransim*"
            - "*hacktool.ransim*"
            - "*riskware.ransomwaresimulator*"
            - "*win32/ransim*"
    condition: selection
level: medium

References & External Analysis

Search "ransim" on VirusTotal (External Analysis)

Frequently Asked Questions

How do I remove the Ransim Ransomware from Windows?

Manual removal of Ransim is highly discouraged as it may leave persistence mechanisms intact. We recommend disconnecting the device from the internet and utilizing a professional incident response service or enterprise-grade EDR software to conduct a full forensic sweep.

Is Ransim a virus or a Ransomware?

Ransim is classified as a Ransomware. Unlike traditional viruses that infect files, modern malware like Ransim typically operates as a standalone payload designed to compromise systems, steal data, or deploy secondary stage implants.

What are the main symptoms of a Ransim infection?

Symptoms of Ransim can include unexpected system slowness, unauthorized outbound network traffic to unknown IP addresses, disabled security software, and suspicious background processes running from AppData or Temp directories.

Related Families (Category: ransomware)

Explore other malware families in the same category:

Protect Your Network Against Ransomwares

Want to prevent Ransim and similar threats from compromising your organization? Read our comprehensive defensive guide: Ransomware Protection Guide.

Need help with an active incident? Published by the SystemHelpdesk team.

Machine-readable

Get this profile as JSON: https://jordanricky1604-ship-it.github.io/malware-families-catalog/api/ransim.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.