Pycrypter
Overview
Executive Summary
PyCrypter is a classification for file-encrypting Ransomware written entirely in Python. While traditionally ransomware was written in C++ or Delphi for speed and low-level system access, the use of Python (often compiled into a standalone executable using tools like PyInstaller or py2exe) has become increasingly common. It allows for rapid development, easy cross-platform porting, and occasionally bypasses older AV engines that struggle to decompile packaged Python scripts.Infection Vector and Technical Capabilities
PyCrypter is typically distributed via targeted spear-phishing campaigns, malicious macros embedded in Office documents, or deployed directly by attackers who have compromised external-facing RDP servers. Upon execution, PyCrypter leverages Python's extensive standard library for its attack:- Standalone Execution: The malware is usually packaged as a bulky `.exe` file. When run, it extracts a temporary Python interpreter and the malicious `.py` scripts into the `%Temp%` directory to execute.
- Cryptographic Implementation: PyCrypter typically utilizes well-known Python cryptography libraries (like `cryptography` or `PyCryptodome`) to implement strong encryption (e.g., AES-256 for files, secured by an RSA public key).
- Volume Shadow Copy Deletion: The Python script will utilize the `os.system` or `subprocess` modules to execute native Windows commands (like `vssadmin delete shadows`) to destroy local backups before encryption begins.
Threat Assessment
Despite being written in a high-level scripting language, PyCrypter is highly destructive. It represents a critical tier-one security incident resulting in an immediate loss of data availability. The use of Python also makes the malware easily modifiable by different threat actors, leading to numerous distinct variants.Incident Response and Remediation
- Immediate Network Severance: Isolate the infected endpoint (and any servers it can reach) from the network to halt the spread of the encryption across mapped drives.
- Reverse Engineering Potential: Because it is written in Python, incident responders may occasionally be able to decompile the executable (using tools like `uncompyle6`) to recover the source code. In rare cases of poor cryptographic implementation, this might reveal a hardcoded key or a flaw allowing for decryption.
- Restore from Offline Backups: Paying the ransom is strongly discouraged. Eradication requires a complete bare-metal wipe of the infected infrastructure and a full restoration from secure, offline backups.
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 T1490 T1059.006
Tactical Mitigations
Based on the techniques used by this family, consider the following defensive strategies:
- T1059.006: 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_PYCRYPTER {
meta:
description = "Detects Pycrypter (ransomware)"
author = "SystemHelpdesk Boilerplate Generator"
date = "2026-07-06"
strings:
$s1 = "pycrypter" ascii wide nocase
$s2 = "ransom.pycrypter" ascii wide nocase
$s3 = "python.ransomware" ascii wide nocase
$s4 = "win32/filecoder.python" ascii wide nocase
condition:
uint16(0) == 0x5a4d and any of them
}Sigma Rule
title: Suspicious Pycrypter Activity
id: 9559abb2bf4d8dbec2042757bd5d9042
status: experimental
description: Detects generic indicators of the pycrypter malware family.
logsource:
category: process_creation
product: windows
detection:
selection:
Image|endswith:
- '\cmd.exe'
- '\powershell.exe'
CommandLine|contains:
- "*pycrypter*"
- "*ransom.pycrypter*"
- "*python.ransomware*"
- "*win32/filecoder.python*"
condition: selection
level: mediumReferences & External Analysis
- Search "pycrypter" on VirusTotal (External Analysis)
Frequently Asked Questions
How do I remove the Pycrypter Ransomware from Windows?
Manual removal of Pycrypter 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 Pycrypter a virus or a Ransomware?
Pycrypter is classified as a Ransomware. Unlike traditional viruses that infect files, modern malware like Pycrypter typically operates as a standalone payload designed to compromise systems, steal data, or deploy secondary stage implants.
What are the main symptoms of a Pycrypter infection?
Symptoms of Pycrypter 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 Pycrypter and similar threats from compromising your organization? Read our comprehensive defensive guide: Ransomware Protection Guide.
Machine-readable
Get this profile as JSON: https://jordan123234-malware-families-explorer.static.hf.space/api/pycrypter.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.