Zaxar

Overview

Executive Summary

Infection Vector and Technical Capabilities

• Process Injection and Hooking: Zaxar heavily utilizes Process Hollowing and API hooking. It decrypts its payload in memory and injects it into legitimate Windows processes (like `explorer.exe` or `svchost.exe`). This allows it to evade file-based AV detection and bypass local firewalls.
• Resilient C2 Communication (DGA): To prevent defenders from simply blocking its Command and Control servers, Zaxar frequently employs Domain Generation Algorithms (DGA). It generates thousands of potential C2 domain names daily, making it extremely difficult to sever its connection to the botmaster.
• Modular Payload Delivery: The Zaxar backdoor is highly modular. The botmaster can dynamically push down specific plugins to the infected endpoint based on its value (e.g., pushing an info-stealer if the machine belongs to the finance department, or a ransomware payload if the machine is a server).

Threat Assessment

Incident Response and Remediation

• Immediate Network Isolation: Instantly sever the network connection of the infected machine to halt the C2 beaconing and prevent the download of the secondary payload.
• Memory Forensics and Telemetry: Because Zaxar operates primarily in memory, traditional file scanning is insufficient. Use EDR telemetry and memory forensics to trace the injected processes and identify all anomalous network connections.
• Mandatory Re-imaging and Credential Reset: The system must be wiped to bare metal and rebuilt from a clean image. All credentials utilized on or by the infected machine must be treated as compromised and immediately reset.

Known aliases

Threat reports may refer to this family under multiple names:

• Botnet.Zaxar
• Trojan.Zaxar
• Backdoor.Win32.Zaxar

MITRE ATT&CK Techniques

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

Tactical Mitigations

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

• T1105: Implement network intrusion detection systems (NIDS) and host-based firewalls to block unauthorized inbound or outbound file transfers.

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_ZAXAR_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Zaxar"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "zaxar" ascii wide nocase
        $s2 = "botnet.zaxar" ascii wide nocase
        $s3 = "trojan.zaxar" ascii wide nocase
        $s4 = "backdoor.win32.zaxar" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Zaxar (Ransomware) Execution & Triage
id: 58230bfb-f34e-5cdc-87ae-1dd6f5c9598d
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Zaxar 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/zaxar
- 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.t1055
- attack.t1568_002
- attack.t1105
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_ZAXAR_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Zaxar 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 = "zaxar" 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 Zaxar 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 Zaxar 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 Zaxar 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 Zaxar 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 Zaxar.
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 Zaxar eradication is completely verified.

References & External Analysis

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

Frequently Asked Questions

Related Threats (Category: Ransomware)

Explore other documented threats in the same operational category:

• Blueeagle
• Zbiw
• Olympicdestroyer
• Hamweq
• Cbot
• Pepex
• Driverupdater
• Agentwdcr

Machine-readable

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