Active threat familyWindowsCredential theft
Malware Intelligence

Katz Stealer

Katz Stealer is an infostealer distributed in 2025 in targeted email campaigns with multi-layer loaders (including PhantomVAI).

Activity map

Palo Alto Networks Unit 42

Activity mapInjectionPackagingExfiltrationPhishing emailOrder, paymentJSScript attachmentVBSScript attachmentPowerShellDownloaderPNGSteganographyPhantomVAI.NET, in memoryKatz StealerInfostealerData collection11 targetsLog archiveC2 server
Executable payloadFile
Malicious payloadKatz Stealer · Infostealer

Katz Stealer is an infostealer distributed in 2025 in targeted email campaigns with multi-layer loaders (including PhantomVAI).

Environment information

  • Operating system
  • Hardware
  • IP and location
  • Installed software
  • Screenshot

Credentials and application data

  • Saved passwords
  • Session cookies
  • Autofill
  • Saved cards
  • Steam
  • Discord
  • Battle.net
  • Telegram
Dark Radar infection records
7,916
Latest infection record
14 October 2026
Malware type
Infostealer
First seen
2025
01

Overview

Ranks 36 of 52 families in Dark Radar data, with 7,916 infection records.

02

Origin and evolution

  1. 2025Distribution with the PhantomVAI loader was documented.Palo Alto Networks Unit 42
03

Technical profile

Malware typeInfostealer
Target operating systemWindows
Primary purposeData theft
Threat categoryCredential theft
First seen2025
Infected systemsWindows 10 95.9%
Public source confidenceLow
04

Targeted applications

11 applications4 categories
05

Data collection

Credentials

  • Browser passwords99.2%Reported
  • Session cookies91.1%Reported
  • Refreshing expired sessions—
  • Autofill96.7%Dark Radar observation
  • macOS Keychain—
  • 2FA and password managers—

Financial

  • Saved cards11.4%Dark Radar observation
  • Desktop crypto wallets3.3%Dark Radar observation
  • Wallet extensions—
  • Clipboard address replacement—

Applications

  • Email clients—
  • FTP clients—
  • VPN clients—
  • Messaging applications24.4%Dark Radar observation
  • Gaming platforms69.1%Dark Radar observation

System

  • File collection—
  • Screenshot36.6%Dark Radar observation
  • System inventory95.9%Dark Radar observation
06

File system

User profile (%USERPROFILE%)
File details are in Dark Radar IntelligenceOpen in Intelligence
07

How it works

  1. 1Infection

    T1566.001Spearphishing Attachment

    Breaking point: Email attachments, sponsored ad links and unlicensed software downloads are blocked at the email and web gateway.

  2. 2Execution and evasion

    Dark Radar observation

    The payload ran from the temporary folder (latest 123 logs, 33.1%).

    Ran from the explorer.exe file in the Windows folder (latest 123 logs, 18.6%).

    Ran from the svchost.exe file in the Windows folder (latest 123 logs, 4.2%).

    T1059.001PowerShellT1620Reflective Code Loading

    Breaking point: Unsigned files running from user folders and injections into .NET tools are stopped by application control and EDR.

  3. 3Discovery

    Dark Radar observation

    Infected systems: Windows 10 95.9%.

    Breaking point: Bulk system and security software queries from a short-lived process trigger an EDR alert.

  4. 4Data collection

    Dark Radar observation

    Data found in the latest 123 logs: password file 99.2%, cookies 91.1%, autofill 96.7%, cards 11.4%, wallets 3.3%.

    T1555.003Credentials from Web Browsers

    Breaking point: A process other than the browser reading browser profile files is blocked or triggers an alert.

08

MITRE ATT&CK

Initial Access
Execution
Defense Evasion
Credential Access
09

IOCs and detection

This section is in Dark Radar IntelligenceOpen in Intelligence
10

Risk and impact

  • Stolen session cookies are enough to take over cloud, email and SaaS sessions without a password or multi-factor authentication prompt.
  • Corporate passwords saved on personal devices also leak through infections outside the corporate network; these logs are sold to initial access brokers.
  • Log archives are reshared for years; as long as the password is not changed, the same credential can be used again and again.
  • Compromised email, messaging and social media accounts become the next link in phishing and malware distribution.
11

Defense

  • When an infection is detected, revoke not only the password but all related sessions and access tokens.
  • Turn off password saving in the browser through corporate policy; use a corporate password manager.
  • Move to phishing-resistant multi-factor authentication (FIDO2/passkey); bind sessions to the device.
  • Block setup files downloaded from unlicensed software, game cheats and sponsored search results.
  • Monitor flows where the user runs a command by pasting it into the Run dialog or terminal (ClickFix) with endpoint rules.
  • Continuously monitor your corporate domains and employee email addresses in stealer logs with Dark Radar.
12

Learning center

How does this malware spread?
  • The payload ran from the temporary folder (latest 123 logs, 33.1%).
  • Infostealer families mostly spread through unlicensed software, fake updates, sponsored search ads and phishing emails.
How can its presence on a system be detected?
  • Sign-ins to accounts from an unrecognized country or device.
  • A new infostealer log in Dark Radar for your corporate domain or an employee email address.
Which Windows artifacts should be examined?
  • Prefetch (C:\Windows\Prefetch) — shows that a short-lived payload ran.
  • Amcache.hve and ShimCache — path and hash of the executed file.
  • Downloads folder and Zone.Identifier stream — the address the file was downloaded from.
  • Browser history — the fake download page or fake CAPTCHA address.
  • RunMRU registry key — commands pasted into the Run dialog.
  • Randomly named folders and DLLs under %TEMP% and %LOCALAPPDATA%.
Which log records matter?
  • Sysmon Event 1 / Security 4688Process creation: unsigned processes starting from Temp and Downloads folders, mshta, powershell -enc chains.
  • Sysmon Olay 11 / 23File creation and deletion: self-deleting payloads, DLLs dropped under Temp.
  • Sysmon Olay 3 / 22Network connection and DNS query: to newly registered domains, C2 resolution via Telegram, Steam or Pastebin.
  • Object access auditing (4663)A process other than the browser reading Login Data, Cookies and Local State files.
  • PowerShell 4104Script block logging: obfuscated downloader commands.
  • Identity provider sign-in logsSessions after the infection from a different country and device, without a multi-factor authentication prompt.
Which MITRE techniques is it associated with?
T1566.001Spearphishing AttachmentT1059.001PowerShellT1620Reflective Code LoadingT1555.003Credentials from Web Browsers
How should a SOC analyst respond?
  1. Isolate the device from the network; do not reinstall it before taking memory and disk images.
  2. Determine the infection date; list all accounts that were signed in on the device after that date.
  3. Change the passwords of these accounts, revoke their sessions and access tokens, and re-enroll multi-factor authentication devices.
  4. Search identity provider and SaaS logs for new country, device and token usage after the infection.
  5. If a recovery phrase or wallet file was exposed, move the assets to a new wallet.
  6. Find the initial access path (email, ad, unlicensed software, fake CAPTCHA) and check other users who used the same path.
  7. Reinstall the device from a clean image.
13

Sources

Related terms

Phishing
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