Zero

Overview

Executive Summary

Infection Vector and Technical Capabilities

• 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

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:

• Rootkit.ZeroAccess
• Trojan.Sirefef
• Win32/ZeroAccess

MITRE ATT&CK Techniques

Observed techniques used by this family, mapped to our technical analysis hubs and the official MITRE ATT&CK framework:

MITRE D3FEND™ Defensive Countermeasures

Defensive techniques mapped to counter the offensive tradecraft observed in this family (via the MITRE D3FEND matrix):

Tiered Detection Rules (Cisco CAIRN Model)

Modern threat detection requires multi-layered rule engineering. We classify detections into three operational tiers based on signal fidelity:

rule MALWARE_WIN_ZERO_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Zero"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    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
}

title: SystemHelpDesk Detection - Zero (Ransomware) Execution & Triage
id: 584773cc-3791-5c85-a576-df38803f1660
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Zero malware family. Detects volume shadow copy deletion, boot status tampering,
  and recovery inhibition characteristic of modern ransomware operations.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/zero
- https://malware-families-catalog.systemhelpdesk.com/defensive/ransomware-protection
- https://malware-families-catalog.systemhelpdesk.com/
author: Ricky Jordan, Lead Threat Intelligence Analyst, SystemHelpDesk MSP
date: '2026-10-14'
modified: '2026-10-14'
tags:
- attack.ransomware
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1014
- attack.t1562_001
- attack.t1090_003
- attack.t1564
logsource:
  category: process_creation
  product: windows
detection:
  selection_process:
    Image|endswith:
    - \vssadmin.exe
    - \wmic.exe
    - \wbadmin.exe
    - \bcdedit.exe
    CommandLine|contains:
    - delete shadows
    - shadowcopy delete
    - resize shadowstorage
    - recoveryenabled no
    - ignoreallfailures
  condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: critical

rule MALWARE_WIN_ZERO_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Zero tradecraft"
        tier = "T3 - Attribution Fingerprint"
        confidence = "High (Confirmed Family Signature)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        // Core family identifier & heuristic payload signatures
        $attrib_str = "zero" ascii wide nocase
        $pe_magic = "MZ" ascii
        $net_marker = "http" ascii nocase
    condition:
        uint16(0) == 0x5a4d and ($attrib_str and $net_marker) and filesize < 15MB
}

Containment & Response Steps

Ordered checklist for responders. Adapt to your environment and engage professional support for active incidents.

1. Immediately isolate affected host(s) from the internal network (disconnect physical Ethernet and disable Wi-Fi/Bluetooth) to prevent Zero from spreading laterally or encrypting network-attached storage (NAS) and shared SMB volumes.
2. Preserve volatile system memory (RAM capture) on a representative endpoint before attempting a reboot or power-down, as Zero symmetric encryption keys or uncompiled payload components may still reside in memory.
3. Audit process execution logs and terminate active scripting interpreters (e.g. PowerShell, CMD, WScript) or commands executing 'vssadmin.exe delete shadows' or 'wbadmin' used by Zero to inhibit recovery.
4. Investigate the initial compromise vector (such as exposed RDP instances, spearphishing attachments, or vulnerable edge gateways) and enforce an immediate credential reset for all compromised Active Directory accounts.
5. Restore critical assets and databases exclusively from verified, air-gapped, or immutable offline backups once the Zero binary and related persistence hooks are eradicated.

What to Avoid

Common mistakes during response to this family that can destroy evidence, spread the infection, or worsen recovery.

1. Do not restart or power cycle infected systems prematurely; doing so destroys volatile RAM encryption keys and may trigger bootloader locking logic embedded in Zero.
2. Avoid negotiating or paying the extortion demand without prior forensic evaluation and consultation with incident response specialists, as payment does not guarantee data recovery.
3. Do not connect clean backup drives or external storage to the affected network until Zero eradication is completely verified.

References & External Analysis

• Search "zero" on VirusTotal (External Analysis)
• Search "zero" on Any.Run (Sandbox Sandbox)
• Search "zero" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Ransomware)

Explore other documented threats in the same operational category:

• Pitin
• Torjok
• Truew
• Zerber
• Cryptojoker
• Donise
• Nsanti
• Rietspoof

Machine-readable

Get this profile as JSON: https://malware-families-catalog.systemhelpdesk.com/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.