If Your Password Is Reused, the Blank-f Stealer Log Should Worry You

HEROIC analysts identified a stealer log file named Blank-f uploaded to a Telegram channel on December 4, 2024. The file contains 166 records, each pairing an email address with a plaintext password, an endpoint URL, and an API host pulled directly from an infected device. Why This Is Dangerous: Unlike a database leak, a stealer log comes straight from malware running on someone's computer, quietly recording login information as it was typed or auto-filled in the browser. That means the credentials in this file were captured at the moment they were actually used, which makes them far more likely to still be active. What Was Exposed: - Email addresses - Plaintext passwords - Endpoint and API host URLs Why This Matters: If your password shows up in this file and you have used it anywhere else, an attacker can immediately attempt credential stuffing against your other accounts. Because stealer log data reflects real, recent logins, it carries a higher chance of still working than credentials from an old, previously reported breach, raising the risk of account takeover, financial fraud, and identity theft. How Stealer Logs Work: Stealer log malware infects a device, often through a fake download, cracked software, or a malicious email attachment, then quietly scans the browser for saved passwords, autofill data, and active login sessions. The malware bundles everything it finds, including the endpoint and API details for each site, into a log file that gets uploaded to Telegram channels like this one, either for sale or as free samples to prove the malware works. Check If You Are Affected: If your password has been sitting unchanged for a while, now is a good time to check. HEROIC's free breach scanner checks your email against more than 400 billion leaked records, including stealer logs like Blank-f, so you can confirm quickly whether your credentials were captured.