Cryptolocker
Overview
CryptoLocker is an early and influential encrypting ransomware that spread widely from 2013, using strong public-key cryptography to lock victims' files. It was distributed largely via the Gameover Zeus botnet and malicious email attachments. In June 2014 the US Department of Justice announced a joint operation that disrupted both Gameover Zeus and CryptoLocker by seizing servers; Evgeniy Bogachev was identified as a leader of the group behind both schemes and is wanted by the FBI.
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 T1566.001 T1083 T1490 T1071.001
Tactical Mitigations
Based on the techniques used by this family, consider the following defensive strategies:
- T1071.001: Implement web filtering and SSL/TLS inspection to detect malicious command and control (C2) traffic hiding in HTTP/HTTPS.
- T1566.001: Scan email attachments for malicious macros, scripts, or suspicious archive files.
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_CRYPTOLOCKER {
meta:
description = "Detects Cryptolocker (ransomware)"
author = "SystemHelpdesk Boilerplate Generator"
date = "2026-07-06"
strings:
$s1 = "cryptolocker" ascii wide nocase
$s2 = "cryptolocker" ascii wide nocase
condition:
uint16(0) == 0x5a4d and any of them
}Sigma Rule
title: Suspicious Cryptolocker Activity
id: a2b823aa40d7db9d17e669784b69b841
status: experimental
description: Detects generic indicators of the cryptolocker malware family.
logsource:
category: process_creation
product: windows
detection:
selection:
Image|endswith:
- '\cmd.exe'
- '\powershell.exe'
CommandLine|contains:
- "*cryptolocker*"
- "*cryptolocker*"
condition: selection
level: mediumReferences & External Analysis
- Malwarebytes Labs: CryptoLocker ransomware
- Search "cryptolocker" on VirusTotal (External Analysis)
Frequently Asked Questions
What is CryptoLocker?
An influential encrypting ransomware, prominent from 2013, that locked files with strong cryptography and demanded payment for the decryption key.
Why is CryptoLocker historically important?
It popularized the modern 'encrypt files and demand cryptocurrency' ransomware model that many later families copied.
How did CryptoLocker spread?
Largely through the Gameover Zeus botnet and malicious email attachments.
How was CryptoLocker disrupted?
In June 2014 a US Department of Justice operation seized servers used by CryptoLocker and disrupted the related Gameover Zeus botnet.
Who was behind CryptoLocker?
The DOJ identified Evgeniy Bogachev as a leader of the group responsible for both CryptoLocker and Gameover Zeus; he is wanted by the FBI.
How can I protect against ransomware like CryptoLocker?
Keep antivirus/anti-malware updated, avoid unknown email attachments, patch your system, and keep tested offline backups.
Where can I read an authoritative source on CryptoLocker?
Malwarebytes Labs published an overview of CryptoLocker, linked on this page.
How do I remove the Cryptolocker Ransomware from Windows?
Manual removal of Cryptolocker 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 Cryptolocker a virus or a Ransomware?
Cryptolocker is classified as a Ransomware. Unlike traditional viruses that infect files, modern malware like Cryptolocker typically operates as a standalone payload designed to compromise systems, steal data, or deploy secondary stage implants.
What are the main symptoms of a Cryptolocker infection?
Symptoms of Cryptolocker 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 Cryptolocker 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/cryptolocker.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.