How the MARVEL_CLOUD MIX LOGS Malware Led to 11,599 Stolen Logins

In November 2023, HEROIC's threat intelligence team identified a stealer log file uploaded to a public Telegram channel under the label MARVEL_CLOUD MIX LOGS. The file contained 11,599 records harvested from compromised endpoints using infostealer malware. Each record included an email address, a plaintext password, and a URL representing the service the victim had been logged into when the infection occured. The data was posted openly on Telegram, making it immediately accessible to any threat actor looking to perform account takeovers or credential stuffing attacks.

Why This Is Dangerous

Stealer logs are among the most immediately actionable types of leaked data. Unlike hashed password dumps that require cracking, these credentials are captured in plaintext and are ready to use the moment an attacker downloads the file. Because the log also includes the URLs of the services each victim was using, attackers do not have to guess where to try the stolen logins -- they already know. With 11,599 records exposed, the scale of potential account takeovers is significant. Victims often do not recieve any warning that their credentials have been captured until accounts are already compromised.

What Was Exposed

The following data types were confirmed in the MARVEL_CLOUD MIX LOGS Telegram upload:

• Email Addresses
• Plaintext Passwords
• URLs (sites and services victims were actively using at time of infection)

Why This Matters

The MARVEL_CLOUD MIX LOGS dump represents a collection of credentials drawn from multiple devices and services. This kind of aggregated stealer log is particularly valuable to attackers because it provides a diverse range of targets in a single file. The 11,599 exposed records include seperate credential pairs from different services, maximizing the number of accounts that can be compromised in a single campaign. Credential stuffing attacks powered by logs like this can impact banking, email, and enterprise systems simultaneously.

How Stealer Log Breaches Work

Infostealer malware spreads through phishing campaigns, malicious software cracks, fake browser updates, and poisoned downloads. Once a device is infected, the malware silently scans browsers, email clients, and apps for saved usernames and passwords. It also captures active session cookies and autofill data. All of this is packaged into a log file and exfiltrated to an attacker-controlled server or uploaded directly to a Telegram channel. The process can be completed in minutes, often before any antivirus tool detects the infection and flags it for the user.

Check If You Are Affected

HEROIC offers a free personal data scanner that checks your email address against more than 400 billion exposed records, including stealer logs like the MARVEL_CLOUD MIX LOGS dump. If your credentials were captured and shared on Telegram, you will receive an immediate alert so you can change your passwords and lock down your accounts. Run a free scan now at heroic.com and find out if your information was part of this breach.