The Monster Cloud Free 2 Stealer Log Ran for Months. Now 12,746 Records Are Public.

In October 2023, an anonymous Telegram user uploaded a stealer log file tied to Monster Cloud Free 2, a cloud storage service used primarily by users in the United States. Security analysts identified the file circulating on a public Telegram channel, where it had been made freely available to anyone who knew where to look. The log contained 12,746 records, each exposing sensitive endpoint data including email addresses, plaintext passwords, and API host URLs. The data was not encrypted or obfuscated in any way, making it immediately usable by anyone who downloaded it.

Why This Is Dangerous

Stealer logs are not just passive data dumps. Attackers actively purchase and trade these files to launch credential stuffing campaigns, targeting email inboxes, cloud dashboards, and any service where a victim reused their password. Because this log includes API host URLs alongside plaintext credentials, a bad actor could gain direct programmatic access to cloud storage environments without triggering standard login alerts. Exposed API credentials are especially valuable because they bypass two-factor authentication entirely. Once inside, attackers can exfiltrate files, plant malware, or sell access to other criminals. The window of exposure begins the moment the log is uploaded, and in this case, that window has been open since October 2023.

What Was Exposed in the Monster Cloud Free 2 Stealer Log

• Email addresses
• Plaintext passwords
• API host URLs
• Endpoint identifiers

Why This Matters

Plaintext passwords are the most dangerous type of credential to have exposed. Unlike hashed passwords, they require no cracking, no GPU time, and no technical skill to use. Anyone with the file can immediatley log in to any account where that password was reused. Research consistently shows that a majority of people reuse passwords across multiple services, which means a single stealer log can cascade into account takeovers across email, banking, social media, and workplace tools. The inclusion of API URLs makes this breach particularly actionable for technically savvy attackers who can automate access at scale.

How Stealer Logs Work

A stealer log is produced by infostealer malware, a type of software designed to silently harvest credentials from an infected device. The malware typically arrives through phishing emails, fake software downloads, or malicious browser extensions. Once installed, it scrapes saved passwords from browsers, desktop apps, and system keychains, then bundles everything into a structured log file. That file is transmitted back to the attacker, who may sell it on dark web forums or upload it to platforms like Telegram for free distribution. The victim often has no idea their device was infected. The malware leaves behind minimal traces and is frequently deleted after the data has been collected. Stealer logs are one of the most common sources of leaked credentials in the world today, and the volume of new logs circulating online continues to grow every year.

Check If You Are Affected

If you have ever used Monster Cloud Free 2 or shared credentials between cloud services and other accounts, your information may be in this log. HEROIC's free breach scanner checks your email against a database of over 400 billion compromised records, including stealer logs like this one. Finding out takes less than a minute, and knowing is the first step to protecting yourself. Run a free scan at HEROIC.com to see if your data has been exposed in this breach or any other.