Pyme

Category: ransomware · Aliases: Worm.Pyme, Trojan.Pyme, Win32/Pyme · Sample count (EMBER 2018): 1 · Enrichment: insufficient_information · Updated: 2026-07-02T07:20:09Z

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

Overview

Executive Summary

Pyme is a malicious program that exhibits characteristics of both a Trojan and a Worm. It is designed to covertly infiltrate Windows systems, establish a persistent backdoor, and then aggressively attempt to propagate itself across local networks or via removable media, creating a disruptive and potentially widespread security incident.

Infection Vector and Technical Capabilities

Pyme often infiltrates networks initially through malicious email attachments or when a user connects an already infected USB drive to a corporate workstation. Upon execution, Pyme focuses on persistence and propagation:

Worm-like Propagation: Pyme actively scans the local subnet for open, unauthenticated file shares (SMB) or exploits legacy vulnerabilities to copy its executable laterally. It will also aggressively infect any connected removable media (USB drives), hiding legitimate files and replacing them with malicious shortcuts to facilitate further spread.
System Modification and Persistence: To ensure it runs every time the system boots, Pyme modifies the Windows Registry (e.g., adding entries to `HKCU\Software\Microsoft\Windows\CurrentVersion\Run`). It may also disable built-in security features like Windows Defender or the Task Manager to protect itself from termination.
Backdoor Functionality: While spreading, Pyme often opens a covert backdoor, allowing remote attackers to issue commands, download secondary malware, or exfiltrate basic system data.

Threat Assessment

A Pyme infection is highly disruptive. Its worm-like propagation capabilities can rapidly saturate a local network, causing significant downtime and overwhelming IT helpdesks. The backdoor functionality also presents a serious risk of data theft or the deployment of secondary, more destructive payloads like ransomware.

Incident Response and Remediation

Immediate Network Segmentation: Isolate infected subnets immediately to halt the worm's lateral movement and prevent the infection of mapped network drives.
Comprehensive Antivirus Sweep: Deploy an enterprise-grade anti-malware solution across the affected subnets to identify, quarantine, and remove the Pyme executable and its associated registry keys.
Removable Media Policy Review: Pyme's reliance on USB propagation strongly suggests that the organization's policies regarding removable media are either lacking or unenforced. Consider disabling USB storage access via Group Policy to prevent future outbreaks.

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: T1059 T1091 T1547.001 T1562.001

Tactical Mitigations

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

T1059: Restrict execution of scripting languages such as PowerShell, VBScript, or Python to authorized administrators. Enforce Script Block Logging.

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_PYME {
    meta:
        description = "Detects Pyme (ransomware)"
        author = "SystemHelpdesk Boilerplate Generator"
        date = "2026-07-06"
    strings:
        $s1 = "pyme" ascii wide nocase
        $s2 = "worm.pyme" ascii wide nocase
        $s3 = "trojan.pyme" ascii wide nocase
        $s4 = "win32/pyme" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

Sigma Rule

title: Suspicious Pyme Activity
id: 46069c1de268ca3157233fcd2e547acb
status: experimental
description: Detects generic indicators of the pyme malware family.
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains:
            - "*pyme*"
            - "*worm.pyme*"
            - "*trojan.pyme*"
            - "*win32/pyme*"
    condition: selection
level: medium

References & External Analysis

Search "pyme" on VirusTotal (External Analysis)

Frequently Asked Questions

How do I remove the Pyme Ransomware from Windows?

Manual removal of Pyme 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 Pyme a virus or a Ransomware?

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

What are the main symptoms of a Pyme infection?

Symptoms of Pyme 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 Pyme 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/pyme.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.