Blackstealer

Overview

Blackstealer (classified in antivirus detection telemetry under designations including PWS:Win32/Blackstealer, PWS.Win32.Blackstealer, and Win32/Blackstealer) is a dedicated information theft malware engineered to harvest stored credentials, browser session cookies, cryptocurrency wallets, and keystrokes. Disseminated across enterprise networks and consumer workstations via social engineering, phishing attachments, malicious drive-by downloads, or weaponized software cracks, Blackstealer executes an initial reconnaissance phase upon system ingress. The binary evaluates host privileges, detects active hypervisors and sandbox environments to evade behavioral analysis, and establishes resilient autostart persistence by configuring registry keys under HKCU\Software\Microsoft\Windows\CurrentVersion\Run or registering background Windows services. Operational mechanics characteristic of this family include credential database extraction, API hooking, system discovery, and encrypted C2 exfiltration. Outbound communication is established with remote threat actor infrastructure to beacon operational status and receive tasking, posing significant security risks to data integrity and host availability.

Known aliases

Threat reports may refer to this family under multiple names:

• Trojan.BlackStealer
• Infostealer.Black
• Win32/Spy.Stealer
• PWS:Win32/Blackstealer
• PWS.Win32.Blackstealer
• Win32/Blackstealer

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_BLACKSTEALER_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Blackstealer"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "blackstealer" ascii wide nocase
        $s2 = "trojan.blackstealer" ascii wide nocase
        $s3 = "infostealer.black" ascii wide nocase
        $s4 = "win32/spy.stealer" ascii wide nocase
        $s5 = "pws:win32/blackstealer" ascii wide nocase
        $s6 = "pws.win32.blackstealer" ascii wide nocase
        $s7 = "win32/blackstealer" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Blackstealer (Infostealer) Execution & Triage
id: a442b79f-6dc6-5249-9bcf-e3bc33d71a1e
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Blackstealer malware family. Detects browser credential database harvesting,
  master key queries, and DPAPI extraction routines typical of modern infostealers.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/blackstealer
- https://malware-families-catalog.systemhelpdesk.com/defensive/infostealer-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.infostealer
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1555
- attack.t1056_001
- attack.t1114
- attack.t1041
- attack.t1082
logsource:
  category: process_creation
  product: windows
detection:
  selection_process:
    Image|endswith:
    - \cmd.exe
    - \powershell.exe
    - \rundll32.exe
    CommandLine|contains:
    - \Google\Chrome\User Data\Default\Login Data
    - \AppData\Roaming\Mozilla\Firefox\Profiles
    - \AppData\Local\Microsoft\Edge\User Data
    - vaultcmd.exe /list
    - dpapi
  condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: high

rule MALWARE_WIN_BLACKSTEALER_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Blackstealer 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 = "blackstealer" 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 Blackstealer 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 Blackstealer 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 Blackstealer 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 Blackstealer 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 Blackstealer.
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 Blackstealer eradication is completely verified.

References & External Analysis

• Microsoft Defender Threat Encyclopedia - PWS:Win32/Blackstealer
• Kaspersky Threat Intelligence - PWS.Win32.Blackstealer
• MITRE ATT&CK - Enterprise Techniques
• Search "blackstealer" on VirusTotal (External Analysis)
• Search "blackstealer" on Any.Run (Sandbox Sandbox)
• Search "blackstealer" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Infostealer)

Explore other documented threats in the same operational category:

• Pony
• Vidar
• Hploki
• Steam
• Ribaj
• Ardamax
• Socelars
• Pirminay

Machine-readable

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