Combolists and ULP Files on the Dark Web A Secondary and Unreliable Source of Information about Compromises

Excerpt:

“Combolists and URL-Login-Password (ULP) files have existed since the earliest user data leaks. These files offer a convenient format for storing and distributing compromised credentials — typically just a username (or email) and password — where all “unnecessary” information is removed. It’s simplicity makes them ideal tools for cybercriminals launching attacks such as credential stuffing, phishing, and other forms of account-based exploitation.

With the advent of modern infostealers, stealing login credentials has become easier and more automated than ever. At the same time, distributing stolen data has been simplified through platforms like dark web forums, file-sharing services, and Telegram channels.

As a result, the release of new combolists and ULP files now happens on an industrial scale. These files often claim to contain billions of fresh, high-quality credentials, continuously feeding the underground market with massive volumes of exploitable user data.

Cybersecurity researchers and threat intelligence firms frequently analyze these combolists and ULP files, issuing warnings about the scale and potential impact of such leaks. However, in practice, combolists and ULP files have largely become outdated and unreliable as sources of new compromise. While they remain a part of the cybercrime ecosystem, the majority of data in these collections is recycled, stale, or poorly verified. For defenders, their true value lies more in historical analysis and credential exposure tracking than in identifying fresh threats.

To read the complete article see: https://www.group-ib.com/blog/combolists-ulp-darkweb/