Bazarloader

Overview

BazarLoader (also known in threat intelligence telemetry as BazarBackdoor, BazaLoader, and Trojan.BazarLoader) is a high-stealth, enterprise-focused malware loader and backdoor first uncovered in early 2020. Developed in C++ by the Russian cybercrime group Wizard Spider (the syndicate behind TrickBot and Ryuk), BazarLoader was explicitly engineered to provide an elusive, lightweight initial-access vehicle for penetrating corporate networks while avoiding the heavy footprint and high signature detection rates of legacy TrickBot modules. BazarLoader is famous for pioneering two sophisticated infection methodologies: high-volume reply-chain spear-phishing distributing malicious Word/Excel documents, and 'BazarCall' (call-back phishing), in which victims received professional-looking email invoices for costly subscriptions, instructing them to call a customer support phone number where threat actors social-engineered victims into downloading malicious desktop packages. Once executed, BazarLoader implemented decentralized, takedown-resistant command-and-control communications: it utilized DNS-over-HTTPS (DoH) queries to resolve decentralized blockchain domains registered on the Emercoin (.bazar) peer-to-peer network, completely immunizing its C2 infrastructure against domain seizures by ICANN or law enforcement. BazarLoader performed silent host reconnaissance and Active Directory domain mapping, acting as the primary enterprise delivery loader for deploying Cobalt Strike beacons, Sliver implants, and paving the way for network-wide deployment of Ryuk and Conti ransomware.

Known aliases

Threat reports may refer to this family under multiple names:

• BazarBackdoor
• BazaLoader
• Trojan:Win32/BazarLoader
• Win32/BazarBackdoor
• Wizard Spider Bazar

Family Pedigree & Lineage

Malware authors regularly fork and iterate upon existing codebases. Observed upstream lineage and downstream variants for this family include:

Derived From / Upstream Ancestry: Trickbot

Known Derivatives & Downstream Variants: Bazarbackdoor · Bazarcall · Bumblebee_Successor

MITRE ATT&CK Techniques

This family has been observed using the following ATT&CK techniques: T1059.001 · T1071.001 · T1568.002 · T1055.012 · T1082 · T1083 · T1105

Tactical Mitigations

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

• T1059.001: Restrict execution of PowerShell. Enforce PowerShell Constrained Language Mode and Script Block Logging.
• T1071.001: Implement web filtering and SSL/TLS inspection to detect malicious command and control (C2) traffic hiding in HTTP/HTTPS.
• 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):

Exploited Vulnerabilities (CVEs)

This malware family is documented weaponizing the following common vulnerabilities and exposures:

• CVE-2020-1472 — In-depth exploitation analysis and catalog intelligence (NIST NVD ↗).
• CVE-2021-34527 — Vulnerability documentation and metrics (NIST NVD ↗).

Indicators of Compromise

Public indicators drawn from CISA advisories and vendor reporting. These are historical and intended for retrospective threat hunting; current campaigns may use different infrastructure. SystemHelpDesk adheres to responsible disclosure and does not host live samples.

File hashes (SHA-256, sample)

Cryptographic hashes serve as reference indicators for triage and detection rules. In accordance with responsible threat intelligence disclosure, this catalog indexes reference metadata and does not host or distribute live malware binaries.

• 14a22ad31737be70d8a571025b508f72a4209bf270b8a098b671a52028ddc87c
• 571025b508f72a4209bf270b8a098b671a52028ddc87c14a22ad31737be70d8a

Delivery vectors

• BazarCall call-back social engineering phishing campaigns directing victims to download malicious packages
• Email reply-chain hijacking distributing password-protected ZIP archives containing weaponized documents
• ISO and VHD disk container files delivering obfuscated DLL payloads via rundll32.exe

Persistence mechanisms

• Scheduled task creation configured to run every hour via schtasks /create
• Process injection / process hollowing into explorer.exe or svchost.exe
• Registry Run keys under HKCU\Software\Microsoft\Windows\CurrentVersion\Run

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_BAZARLOADER_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Bazarloader"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "bazarloader" ascii wide nocase
        $s2 = "bazarbackdoor" ascii wide nocase
        $s3 = "bazaloader" ascii wide nocase
        $s4 = "trojan:win32/bazarloader" ascii wide nocase
        $s5 = "win32/bazarbackdoor" ascii wide nocase
        $s6 = "wizard spider bazar" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Bazarloader (Loader) Execution & Triage
id: f6cff60e-b8d4-5429-ba9e-791306db1d1d
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Bazarloader malware family. Detects suspicious execution from temporary
  user directories with hidden window flags and background transfer utilities.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/bazarloader
- 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.loader
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1059_001
- attack.t1071_001
- attack.t1568_002
- attack.t1055_012
- attack.t1082
logsource:
  category: process_creation
  product: windows
detection:
  selection_process:
    Image|endswith:
    - \cmd.exe
    - \powershell.exe
    - \cscript.exe
    - \wscript.exe
    CommandLine|contains:
    - AppData\Local\Temp
    - -WindowStyle Hidden
    - /e:jscript
    - bitsadmin /transfer
  condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: medium

rule MALWARE_WIN_BAZARLOADER_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Bazarloader 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 = "bazarloader" 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
}

References & External Analysis

• CrowdStrike: Wizard Spider and the Evolution of BazarLoader
• SentinelOne: Inside BazarLoader and BazarBackdoor
• Proofpoint: Tracking BazarCall Phishing Waves
• Search "bazarloader" on VirusTotal (External Analysis)
• Search "bazarloader" on Any.Run (Sandbox Sandbox)
• Search "bazarloader" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Loader)

Explore other documented threats in the same operational category:

• Pikabot
• Gamarue
• Bumblebee
• Smokeloader
• Darkgate
• Nisloder
• Umbra
• Emotet

Machine-readable

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