Zero
Overview
Executive Summary
While "Zero" can occasionally refer to minor ransomware variants, in enterprise security contexts, it most commonly refers to the ZeroAccess botnet (also known as Sirefef). ZeroAccess is a highly sophisticated, kernel-level rootkit designed to completely subjugate Windows systems. Its primary objective is to create a massive peer-to-peer (P2P) botnet utilized for highly profitable click fraud campaigns and Bitcoin mining, operating entirely invisibly to the user.Infection Vector and Technical Capabilities
ZeroAccess is typically distributed via exploit kits (like Blackhole) hosted on compromised websites, which silently exploit unpatched browser or Java vulnerabilities. It is also distributed via malicious software bundlers on peer-to-peer networks. Upon execution, ZeroAccess employs advanced, highly destructive rootkit techniques:- Kernel-Level Hooking: The malware injects itself deep into the Windows operating system core (Ring 0). It actively overwrites critical system drivers (like `tcpip.sys`) to intercept and manipulate network traffic.
- Security Software Neutralization: ZeroAccess aggressively hunts for and terminates processes associated with antivirus and EDR solutions. It also actively blocks updates to Windows Defender and other security tools.
- Hidden Volumes: It creates hidden, encrypted volumes within the Windows file system (often masquerading as Recycle Bin data) to store its configuration files, downloaded payloads, and the stolen click-fraud data, making it invisible to standard file explorers and basic AV scans.
- P2P Communication: Rather than relying on a centralized C2 server that can be easily taken down, infected nodes communicate directly with each other via a custom P2P protocol to receive updates and new instructions.
Threat Assessment
A ZeroAccess infection is a critical compromise of system integrity. The malware's ability to operate at the kernel level means it completely controls the operating system's reality. It causes severe network congestion (due to P2P chatter and click fraud traffic) and leaves the machine completely defenseless against other malware.Incident Response and Remediation
- Immediate Network Severance: Isolate the endpoint to halt the click fraud traffic and prevent it from acting as a node in the P2P botnet.
- Do Not Attempt Cleaning: Because ZeroAccess overwrites critical system drivers and utilizes encrypted rootkit volumes, attempting to manually clean the infection or run standard AV removal tools will almost certainly result in a permanently unbootable system (Blue Screen of Death).
- Total Re-imaging: The only secure and reliable remediation for a ZeroAccess/Sirefef infection is a complete bare-metal wipe of the hard drive and a fresh OS installation from a known-good baseline.
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: T1014 T1562.001 T1090.003 T1564
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_ZERO {
meta:
description = "Detects Zero (ransomware)"
author = "SystemHelpdesk Boilerplate Generator"
date = "2026-07-06"
strings:
$s1 = "zero" ascii wide nocase
$s2 = "rootkit.zeroaccess" ascii wide nocase
$s3 = "trojan.sirefef" ascii wide nocase
$s4 = "win32/zeroaccess" ascii wide nocase
condition:
uint16(0) == 0x5a4d and any of them
}Sigma Rule
title: Suspicious Zero Activity
id: d02c4c4cde7ae76252540d116a40f23a
status: experimental
description: Detects generic indicators of the zero malware family.
logsource:
category: process_creation
product: windows
detection:
selection:
Image|endswith:
- '\cmd.exe'
- '\powershell.exe'
CommandLine|contains:
- "*zero*"
- "*rootkit.zeroaccess*"
- "*trojan.sirefef*"
- "*win32/zeroaccess*"
condition: selection
level: mediumReferences & External Analysis
- Search "zero" on VirusTotal (External Analysis)
Frequently Asked Questions
How do I remove the Zero Ransomware from Windows?
Manual removal of Zero 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 Zero a virus or a Ransomware?
Zero is classified as a Ransomware. Unlike traditional viruses that infect files, modern malware like Zero typically operates as a standalone payload designed to compromise systems, steal data, or deploy secondary stage implants.
What are the main symptoms of a Zero infection?
Symptoms of Zero 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 Zero and similar threats from compromising your organization? Read our comprehensive defensive guide: Ransomware Protection Guide.
Machine-readable
Get this profile as JSON: https://jordanricky1604-ship-it.github.io/malware-families-catalog/api/zero.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.