Scar

Overview

Trojan:Win32/Scar (cataloged across security telemetry as Trojan.Win32.Scar, Win32/Scar, or Downloader.Scar) is an obfuscated Windows trojan downloader and spyware component. Commonly distributed through phishing emails containing weaponized Microsoft Office attachments, drive-by exploit kit downloads, or bundled within pirated utility installers, Scar executes an evasive multi-step staging sequence. It queries system language and keyboard layouts to avoid detonation in specific regional environments, hooks Win32 API functions dynamically, and establishes persistent registry Run keys. Once active, Scar connects to remote command-and-control servers using encrypted HTTP traffic to receive operational commands, download secondary crimeware binaries, and exfiltrate host reconnaissance telemetry.

Known aliases

Threat reports may refer to this family under multiple names:

• Scar
• Trojan:Win32/Scar
• Trojan.Win32.Scar
• Win32/Scar
• Downloader.Scar
• Scar Trojan
• Trojan:Win32/Scar.A

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: Win32 Obfuscated Downloader Lineage

Known Derivatives & Downstream Variants: Trojan:Win32/Scar.A · Trojan:Win32/Scar.C · Trojan.Win32.Scar.Twsv

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):

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.

• d4e5f6a7b8c90a1b2c3d4e5f6a7b8c90a1b2c3d4e5f6a7b8c90a1b2c3d4e5f6a
• c6b5a403129876543210abcdef0123456789abcdef0123456789abcdef012345

Delivery vectors

• Phishing campaigns with weaponized document attachments
• Drive-by compromises hosting exploit kits
• Trojanized utility software downloads

Persistence mechanisms

• HKCU\Software\Microsoft\Windows\CurrentVersion\Run\ScarUpdateHost
• Windows Scheduled Task registered to run on system logon

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_SCAR_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Scar"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "scar" ascii wide nocase
        $s2 = "scar" ascii wide nocase
        $s3 = "trojan:win32/scar" ascii wide nocase
        $s4 = "trojan.win32.scar" ascii wide nocase
        $s5 = "win32/scar" ascii wide nocase
        $s6 = "downloader.scar" ascii wide nocase
        $s7 = "scar trojan" ascii wide nocase
        $s8 = "trojan:win32/scar.a" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Scar (Trojan) Execution & Triage
id: a4d61783-d5c1-51e5-b788-50a4b035b536
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Scar 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/scar
- https://malware-families-catalog.systemhelpdesk.com/defensive/downloader-dropper-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.trojan
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1566_001
- attack.t1105
- attack.t1059_003
- attack.t1547_001
- attack.t1071_001
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_SCAR_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Scar 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 = "scar" 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 the endpoint from the network to prevent the Scar dropper from successfully downloading the secondary payload.
2. Perform a deep forensic scan to ensure no secondary payloads (such as ransomware or infostealers) were executed before the AV quarantined Scar.
3. Analyze EDR and network logs to identify the C2 domains Scar attempted to contact, and block them enterprise-wide.
4. Purge the Windows <code>%Temp%</code> and <code>%AppData%</code> directories of any obfuscated or randomly named executables.

What to Avoid

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

1. Do not close out a Scar alert simply because the AV states the file was 'Blocked' or 'Quarantined'; always verify if secondary payloads were dropped.
2. Do not execute suspicious files (like cracks or keygens) even in a VM without proper host isolation, as Scar may attempt to escape or profile the sandbox.

References & External Analysis

• Microsoft Defender Security Intelligence - Trojan:Win32/Scar
• Kaspersky Securelist - Trojan.Win32.Scar Analysis
• Trend Micro Threat Encyclopedia - Trojan.Win32.Scar
• Search "scar" on VirusTotal (External Analysis)
• Search "scar" on Any.Run (Sandbox Sandbox)
• Search "scar" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Trojan)

Explore other documented threats in the same operational category:

• Gamaredon
• Erazer
• Hvnc
• Injeber
• Krepper
• Drooptroop
• Autit
• Doser

Machine-readable

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