Pirminay

Overview

Pirminay (classified across security vendors as Trojan:Win32/Pirminay and PWS:Win32/Pirminay) is an information-stealing trojan designed to covertly harvest system credentials, cached passwords, and sensitive browser session tokens from Windows hosts. Distributed via spear-phishing emails containing malicious invoice attachments or weaponized macro documents, Pirminay executes environment discovery upon launch. It scrapes stored credentials from major web browsers (Chrome, Firefox, Edge), email clients (Outlook, Thunderbird), and Windows Credential Manager. It encrypts collected data with AES/XOR and exfiltrates it to remote command-and-control servers over HTTP/HTTPS POST requests.

Known aliases

Threat reports may refer to this family under multiple names:

• Trojan:Win32/Pirminay
• PWS:Win32/Pirminay
• Trojan-PSW.Win32.Pirminay
• Pirminay Stealer
• Win32/Pirminay

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_PIRMINAY_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Pirminay"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "pirminay" ascii wide nocase
        $s2 = "trojan:win32/pirminay" ascii wide nocase
        $s3 = "pws:win32/pirminay" ascii wide nocase
        $s4 = "trojan-psw.win32.pirminay" ascii wide nocase
        $s5 = "pirminay stealer" ascii wide nocase
        $s6 = "win32/pirminay" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Pirminay (Infostealer) Execution & Triage
id: eaeadcab-1b0f-59e5-801c-0e953155cc35
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Pirminay 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/pirminay
- 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_003
- attack.t1555_004
- attack.t1547_001
- attack.t1059_003
- attack.t1041
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_PIRMINAY_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Pirminay 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 = "pirminay" 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. Quarantine the endpoint to halt the active exfiltration of browsing telemetry and the downloading of further adware modules.
2. Audit Windows Group Policies and the Registry to remove any forced extension installation policies created by the adware.
3. Deploy an enterprise adware removal tool (e.g., AdwCleaner) to locate and strip the deeply embedded registry hooks and watchdog services.
4. Force a complete reset of all installed web browsers to factory defaults to eradicate the rogue extensions and restore the homepage.

What to Avoid

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

1. Do not rely solely on the browser's 'remove extension' button; Pirminay frequently uses GPOs and watchdog services to immediately reinstall itself.
2. Avoid ignoring the infection; adware tracking data is highly detailed and may expose corporate activities or access to internal portals.

References & External Analysis

• Microsoft Defender Threat Encyclopedia - Trojan:Win32/Pirminay
• Trend Micro Security Research - PWS.Win32.Pirminay Overview
• MITRE ATT&CK - Credentials from Password Stores (T1555)
• Search "pirminay" on VirusTotal (External Analysis)
• Search "pirminay" on Any.Run (Sandbox Sandbox)
• Search "pirminay" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Infostealer)

Explore other documented threats in the same operational category:

• Advpassman
• Agenttesla
• Qqpass
• Khalesi
• Urelas
• Razy
• Browserpassview
• Stealc

Machine-readable

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