Vidarstealer

Overview

Executive Summary

Infection Vector and Technical Capabilities

• Browser Targeting: Vidar aggressively targets nearly all modern web browsers (Chrome, Firefox, Edge, Opera, Brave). It extracts saved passwords, autofill data, credit card numbers, browsing history, and critically, active session cookies (allowing attackers to bypass MFA).
• Wallet Extraction: The stealer is explicitly designed to locate and steal the `wallet.dat` files and recovery phrases associated with dozens of desktop cryptocurrency wallets (e.g., Bitcoin Core, Electrum, Exodus).
• Application Data: It harvests credentials from FTP clients (FileZilla), email clients (Thunderbird, Outlook), and secure messaging applications (Telegram, Signal).
• Exfiltration and Evasion: The stolen data is compiled into a ZIP archive and transmitted to a C2 server (often utilizing Telegram or Mastodon APIs for covert C2 communication). Once exfiltration is complete, Vidar typically deletes its own executable and the temporary archive to hinder incident response.

Threat Assessment

Incident Response and Remediation

• Assume Total Compromise: Because Vidar steals session cookies, simply changing passwords is insufficient. All active sessions across all web services (M365, Google Workspace, banking portals) must be forcefully terminated, followed by a comprehensive password reset.
• Cryptocurrency Asset Movement: If the user managed cryptocurrency on the infected machine, those assets must be immediately transferred to a new, secure wallet, as the private keys are now in the hands of the attackers.
• Forensic Analysis: While Vidar often self-deletes, forensic analysis of network logs (PCAPs) can identify the specific C2 infrastructure used for exfiltration, aiding in the generation of IOCs.

Known aliases

Threat reports may refer to this family under multiple names:

• Trojan.Vidar
• Spyware.VidarStealer
• PWS.Win32.Vidar

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:

• T1056.001: Implement Endpoint Detection and Response (EDR) to monitor for suspicious API calls related to keystroke interception. Enforce Multi-Factor Authentication (MFA) to render stolen passwords useless.

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_VIDARSTEALER_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Vidarstealer"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "vidarstealer" ascii wide nocase
        $s2 = "trojan.vidar" ascii wide nocase
        $s3 = "spyware.vidarstealer" ascii wide nocase
        $s4 = "pws.win32.vidar" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Vidarstealer (Advanced Threat) Execution & Triage
id: 2990f093-d55b-50c1-b834-a887a0b6cbee
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Vidarstealer malware family. Detects proxy execution, reflective DLL loading,
  and remote command injection associated with modular enterprise backdoors.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/vidarstealer
- https://malware-families-catalog.systemhelpdesk.com/defensive/backdoor-rat-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.advanced-threat
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1056_001
- attack.t1552_001
- attack.t1539
- attack.t1048
logsource:
  category: process_creation
  product: windows
detection:
  selection_process:
    Image|endswith:
    - \powershell.exe
    - \cmd.exe
    - \rundll32.exe
    - \regsvr32.exe
    CommandLine|contains:
    - DownloadString
    - IEX(
    - '/s /n /u /i:'
    - sc create
    - start-process
  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_VIDARSTEALER_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Vidarstealer 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 = "vidarstealer" 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. Enforce forensic network isolation on all suspected endpoints while maintaining an out-of-band telemetry conduit to capture live Vidarstealer adversary activity.
2. Perform full memory dumps across identified staging nodes to extract memory-only implants, kernel rootkit hooks, and decrypted Vidarstealer C2 infrastructure IP/domain lists.
3. Review Active Directory domain controller authentication logs for anomalous Kerberos ticket requests (Pass-the-Ticket, Golden Ticket) and unauthorized DCSync operations associated with Vidarstealer.
4. Block all confirmed C2 domains, dynamic DNS endpoints, and proxy IP addresses across perimeter firewalls, proxies, and DNS security gateways.
5. Conduct an enterprise-wide sweep across surrounding subnets for secondary webshells, WMI event subscriptions, or remote execution tooling left behind by Vidarstealer operators.

What to Avoid

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

1. Do not assume the incident is resolved simply because an antivirus tool removed the initial Vidarstealer dropper; always verify that secondary payloads and persistence hooks have been eradicated.
2. Avoid logging in with Domain Admin or privileged credentials on a machine suspected of running Vidarstealer until memory triage is complete.
3. Do not delay host isolation; automated lateral movement and credential dumping can occur within minutes of initial execution.

References & External Analysis

• Search "vidarstealer" on VirusTotal (External Analysis)
• Search "vidarstealer" on Any.Run (Sandbox Sandbox)
• Search "vidarstealer" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Advanced Threat)

Explore other documented threats in the same operational category:

• Widgi
• Exfriendalert
• Elitekeylogger
• Crawler
• Fakesysdef
• Blackenergy
• Babar
• Vprotect

Machine-readable

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