🔥 MALWARE ANALYSIS • INFOSTEALER THREAT

PASSWORD CRISIS: Shuyal Stealer Attacking 19 Major Browsers to Harvest All Your Login Credentials

By CyberDudeBivash • October 09, 2025 • V6 “Leviathan” Deep Dive

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Definitive Guide: Table of Contents

Part 1: The Executive Briefing — The Business of Stolen Credentials

A new and highly prolific information stealer, which we have dubbed **”Shuyal Stealer”** (from the Bengali for “Vulture”), is at the center of a massive new credential harvesting campaign. Delivered via malvertising and fake software installers, this malware is a digital predator designed to do one thing with ruthless efficiency: “prey” on a compromised system and “pick it clean” of all valuable credentials. It targets the saved passwords, session cookies, and cryptocurrency wallets from over 19 major web browsers and a growing list of desktop applications.

For CISOs, this is not just a consumer-grade threat. A single employee’s computer infected with Shuyal can lead to the immediate compromise of their corporate VPN, email, and SaaS application credentials. Stolen credentials are the number one initial access vector for major ransomware attacks and nation-state intrusions. The widespread availability of potent infostealers like Shuyal means that you must operate under the assumption that your employees’ passwords *will* be compromised. This is the new reality of the password crisis.

Part 2: Technical Deep Dive — How Shuyal Steals Passwords from Browsers

To understand the threat, you must understand how modern infostealers operate. They are not guessing passwords; they are stealing them directly from the browser’s own storage.

How Chromium-Based Browser (Chrome, Edge, Brave, etc.) Theft Works

Shuyal’s primary target is the user’s profile directory. The process is a surgical strike:

Steal the Key:** The malware first navigates to the `User Data` directory and reads the `Local State` file. This JSON file contains the AES encryption key, which is itself encrypted with the Windows Data Protection API (DPAPI). The malware calls the standard `CryptUnprotectData` function to decrypt this key.
**Find the Database:** It then locates the `Login Data` file. This is a simple SQLite database that contains a table with three important columns: the origin URL, the username, and the `password_value`.
**Decrypt and Exfiltrate:** The `password_value` is encrypted with the key stolen in step 1. The malware iterates through the database, decrypts every password, and packages the entire list (URL, username, plaintext password) for exfiltration to its command-and-control server.

How Firefox Theft Works

The process for Firefox is similar but targets different files:

Locate the Profile:** The malware finds the active Firefox profile directory.
**Steal the Keys and Logins:** It copies two key files: `key4.db` (which contains the decryption keys) and `logins.json` (which contains the encrypted passwords).
**Offline Decryption:** The malware exfiltrates these two files to the attacker, who can then use an open-source tool to decrypt the `logins.json` file using the keys from `key4.db`.

Part 3: The Defender’s Playbook — A Guide for Users and SOC Teams

Defending against this threat requires action from both the individual user and the corporate security team.

For All Users: Your Personal Defense

STOP SAVING PASSWORDS IN YOUR BROWSER. This is the root cause of the problem. Use a dedicated, encrypted password manager instead.
MANDATE PHISHING-RESISTANT MFA.** This is your most powerful defense. Even if an attacker steals your password, they cannot log in without your physical hardware key. This is a non-negotiable for all critical accounts.
**Be Skeptical of Downloads:** Only download software from the official vendor website. If a search result leads you to a third-party download portal, it is likely a trap.
**Use a Modern Security Suite:** A high-quality antivirus is essential for detecting and blocking the trojanized installers that deliver Shuyal.

The Unphishable Defense: Deploying hardware security keys is the gold standard for protecting your most valuable accounts.

Shop for FIDO2 Security Keys →

For SOC Teams: The Enterprise Hunt

You must hunt for the malware’s behavior on the endpoint.

**Hunt for the Dropper:** Monitor for users downloading executables from newly registered or uncategorized domains.
**The Golden Signal:** The most high-fidelity hunt is to look for any process *other than the browser itself* attempting to read the browser’s core data files. An EDR query for this is your best weapon:ProcessName NOT IN ('chrome.exe', 'msedge.exe', 'firefox.exe') AND FileRead CONTAINS ('AppData\Local\Google\Chrome\User Data\Local State', 'AppData\Roaming\Mozilla\Firefox\Profiles\logins.json')

Part 4: The Strategic Takeaway — Why the Password is Dead

For CISOs, the proliferation of potent infostealers like Shuyal is the final nail in the coffin for the password as a viable security control. You must operate your security program under the assumption that your users’ passwords have been, or will be, compromised. This is not a hypothetical; it is an inevitability.

This reality makes two strategic initiatives a non-negotiable mandate for the modern enterprise:

**A Move to Passwordless / Phishing-Resistant MFA:** You must accelerate your deployment of FIDO2 and other passwordless authentication methods. This is the only technical control that truly solves the credential theft problem at its root.
**A Zero Trust Architecture:** Because you must assume credentials will be stolen, you cannot trust any login, even one with a valid password. A Zero Trust model that continuously verifies user and device context before granting access to sensitive resources is the only resilient architectural approach.

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About the Author

CyberDudeBivash is a cybersecurity strategist with 15+ years in malware analysis, reverse engineering, and identity security, advising CISOs across APAC. [Last Updated: October 09, 2025]

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