If You Reuse Passwords, the KURZL0G Stealer Log Should Worry You

HEROIC analysts tracked a stealer log file uploaded to Telegram on November 18, 2025, under the name BONUS ULP UP_KURZL0G. This was the seventh part of a multi-file release, and this segment alone contained 1,558,264 records. Each record included an email address, a plaintext password, and the URL of the site where that login was used. The scale of this single file part -- over 1.5 million entries -- puts it among the larger single-session uploads HEROIC has catalogued from Telegram-based threat actors.

Why Reusing Passwords Makes the KURZL0G Release Particularly Threatening

A stealer log of this size is not just a threat to the original sites where the credentials were harvested. It is a threat to every account the victim owns. If you use the same password for your work email, your bank, and your streaming service, an attacker who finds your entry in this file gains access to all three simultaneously. Password reuse turns a single compromised credential into a master key. With over 1.5 million entries in just this one file -- and several other parts in the same series -- the number of unique individuals at risk is significant.

What Was Exposed in the KURZL0G Part 7 Stealer Log

• Email addresses
• Plaintext passwords (no encryption, no cracking needed)
• URLs of the services each login belongs to

Why Multi-Part Releases Signal an Organized Threat Operation

When a stealer log is released in numbered parts, it is a sign that the operation behind it is organized and ongoing. The KURZL0G series suggests a threat actor running a sustained harvesting campaign rather than a one-off breach. Part 7 implies at least six earlier files were released, potentially exposing millions more credentials across the full series. Organized operations like this one typically have buyers lined up before the files even go public, meaning the credentials may already be in use by the time the breach becomes publicly known.

How Multi-Part Stealer Log Campaigns Operate

Large-scale stealer log operations work by deploying malware across many victims simultaneously -- through phishing emails, malicious downloads, or compromised websites. As the malware phones home with harvested data, the operator accumulates a growing archive of credentials. Rather than releasing everything at once, operators package the logs into numbered batches and release them over days or weeks. This builds reputation on criminal forums and generates sustained demand. Each part is typically validated before release, meaning the credentials in this file were confirmed as useable at some point before being shared on Telegram. The use of an unusual filename like KURZL0G may be an alias or brand identifier used by this particuler operator.

See If Your Email Appeared in the KURZL0G Release

With 1.5 million records in just one part of a multi-file series, the probability that someone you know was affected is not small. HEROIC's free breach scanner checks your email against more than 400 billion exposed records, including this stealer log series and thousands of other known breaches. It takes seconds. Enter your email address now and find out whether you need to change your passwords before an attacker does it for you.