How the 39 Boss Stealer Malware Led to 1,600 Stolen Logins on Telegram

HEROIC analysts found 1,600 records in the 39 Boss stealer log, leaked on August 23, 2023. Uploaded to Telegram, this file exposed email addresses, plaintext passwords, and the URLs each credential was harvested from -- collected by malware running silently on victims' devices.

Why 39 Boss Stealer Log Data Is Dangerous

Even at 1,600 records, a stealer log like 39 Boss poses a direct threat to everyone in it. The passwords are stored in plain text -- exactly as they were typed -- paired with the websites they unlock. A criminal who downloads this file does not need any technical skill to exploit it. The data is already organized and ready to use for login attempts across any site that shares a password with the ones recorded here.

What Was Exposed in the 39 Boss Breach

• Email addresses
• Plaintext (unencrypted) passwords
• URLs identifying which sites each credential was stolen from
• API endpoints and host data extracted from infected machines

Why the 39 Boss Leak Matters

Stealer log data like the 39 Boss file feeds directly into credential stuffing attacks, where automated tools test stolen logins across dozens of platforms without any human intervention. If a password in this file was also used on your email account, your bank, or any account tied to a payment method, those accounts are vulnerable. Account takeover can happen within hours of a log being distributed. Identity theft and financial fraud frequently follow when attackers gain access to email accounts, which serve as the key to resetting nearly every other account a victim owns.

How Stealer Logs Led to the 39 Boss Leak

The 39 Boss file did not come from a hacked company database. It was built record by record from individual devices infected with information stealer malware. A victim encountered the malware through an ordinary-looking download, a phishing link, or a browser extension that quietly ran in the background. The malware then extracted every password stored in the browser, captured active session cookies, and collected API credentials and host data it found on the machine. It packaged all of that into a structured log file and transmitted it back to the attacker. The attacker compiled these individual logs under the 39 Boss name and shared the resulting file on Telegram in August 2023, where it entered circulation among criminal buyers.

Check If Your Data Was Exposed

HEROIC's free breach scanner checks your email address against more than 400 billion exposed records, including stealer logs like 39 Boss. If your credentials are in this file, you will want to know before someone else uses them. A quick search at HEROIC takes seconds and can tell you whether your email has appeared in any known breach dataset. Run a free check now.