Blasterx

Overview

BlasterX is a variant of the notorious Blaster worm that caused widespread disruption on the internet in the early 2000s. Operating as a network worm, BlasterX rapidly self-propagates by exploiting vulnerabilities in the Windows DCOM RPC service, requiring no user interaction to infect vulnerable systems. Once a machine is compromised, the worm executes a payload designed to participate in Distributed Denial of Service (DDoS) attacks, often targeting specific infrastructure or websites. A hallmark of the Blaster family is its ability to cause systems to repeatedly crash and reboot, leading to significant downtime and loss of productivity. The rapid spread of BlasterX highlighted critical flaws in patch management practices, underscoring the absolute necessity for organizations and home users to promptly apply security updates released by software vendors.

Known aliases

Threat reports may refer to this family under multiple names:

• W32.Blaster.X
• Lovsan Variant

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: Blaster_Lovsan_Worm

Known Derivatives & Downstream Variants: W32.Blaster.B · W32.Blaster.C · W32.Blaster.F

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):

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.

• e2b5d4c81a9f0e3b6a7c8d9e0f1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a
• f3c6e5d92b0a1f4c7b8d9e0f1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b

Delivery vectors

• Direct remote exploitation of TCP port 135 (DCOM RPC) across public and intranet IP subnets
• Automated port scanning targeting Microsoft Windows 2000 and Windows XP endpoints

Persistence mechanisms

• HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\windows auto update = msblast.exe
• Remote execution via TFTP payload transfer following RPC exploit shellcode execution

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_BLASTERX_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Blasterx"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "blasterx" ascii wide nocase
        $s2 = "w32.blaster.x" ascii wide nocase
        $s3 = "lovsan variant" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Blasterx (Worm) Execution & Triage
id: f7891557-ae07-5680-aa02-6d8c2486a908
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Blasterx 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/blasterx
- 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.worm
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1210
- attack.t1498
- attack.t1489
- attack.t1190
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_BLASTERX_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Blasterx 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 = "blasterx" 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. Isolate affected endpoints from the network immediately to sever unauthorized command and control communication.
2. Identify and terminate active Blasterx binaries and associated parent-child process chains.
3. Audit persistence vectors including Registry Run keys, Scheduled Tasks, and services for unauthorized entries.
4. Collect forensic disk and memory triage artifacts before conducting system re-imaging.

What to Avoid

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

1. Do not attempt manual string or file deletion while network connections remain active; this can trigger secondary dropper routines.
2. Avoid restoring from backups without verifying that the backup snapshot predates initial Blasterx installation.

References & External Analysis

• CISA Alert (TA03-223A) - W32/Blaster Worm Analysis
• NIST National Vulnerability Database - CVE-2003-0352 Details
• Symantec Security Response - W32.Blaster.Worm Profile
• Search "blasterx" on VirusTotal (External Analysis)
• Search "blasterx" on Any.Run (Sandbox Sandbox)
• Search "blasterx" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Worm)

Explore other documented threats in the same operational category:

• Kolabc
• Warezov
• Xorer
• Sasser
• Blaster
• Benjamin
• Brambul
• Mofksys

Machine-readable

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