Inside blackcloud_001public4: How Infostealer Malware Stole 9,207 Passwords

In July 2023, HEROIC analysts identified a stealer log file named blackcloud_001public4 that had been uploaded to Telegram by an anonymous user. The file contained 9,207 records taken from compromised computers in the United States. Exposed data included email addresses, plaintext passwords, and the URLs of the websites where the credentials were originaly harvested by the malware.

Why This Is Dangerous

When passwords are captured by a stealer and exposed in plaintext, there is no safety net. Unlike a hashed password database where some protection exists, these credentials are ready to use the moment an attacker downloads the file. The blackcloud_001public4 log represents real, active logins that were silently stolen from real people's computers.

What Was Exposed

• Email Addresses
• Plaintext Passwords
• URLs (showing exactly which sites were targeted)

Why This Matters

Stealer logs like blackcloud_001public4 are a primary fuel source for credential stuffing campaigns, account takeover attacks, and identity theft operations. Criminals who obtain these files test the email and password pairs across banking sites, shopping platforms, and social media. If a password was reused anywhere, every account using that password is now compromised. Financial fraud often follows shortly after account access is gained.

How Stealer Logs Work

Infostealers are a category of malware designed specifcally to collect login credentials from infected computers. They spread through phishing emails, cracked software downloads, malicious browser extensions, and fake game mods. Once installed, the malware runs quietly in the background, monitoring the browser and recording every username and password submitted on any website. It also notes the URL of each site, giving attackers a map of exactly where to use the stolen credentials. The collected data is bundled into a structured log file, often labeled with a name like blackcloud_001public4, and sent to the attacker's server. These log files are routinely sold in bulk or shared for free on Telegram channels, as happened with this breach in July 2023.

Check If You Are Affected

HEROIC's free breach scanner covers more than 400 billion exposed records and includes stealer log databases like blackcloud_001public4. Enter your email address to check whether your credentials appeared in this file or any other known breach. The sooner you know, the sooner you can change passwords and protect your accounts.