Cit0day Archive Part 11 Still Fuels Credential Stuffing Attacks Today

HEROIC analysts spotted another piece of the Cit0day archive making the rounds, this one labeled Premium.part11, holding 3,878 email and password pairs. Cit0day was a paid combolist indexing service that operated for years before it was shut down, and fragments of its catalog, like this part11 file, still get redistributed on Telegram today. The passwords in this piece are stored in plaintext, dated 10 Oct 2023.

Why a Years-Old Archive Piece Is Still Dangerous

Cit0day's whole business model was making stolen credentials easy to search and buy, so fragments like this were built for exactly the kind of automated abuse that still works today. A password that has not been changed since it first appeared in Cit0day's catalog is just as usable to an attacker now as it was the day it was indexed.

What This Piece of the Archive Contains

• Email addresses identify which accounts this fragment covers and fuel targeted phishing attempts.
• Plaintext passwords require no cracking, so an attacker can start testing them immediately.
• URLs show which site each login was meant for, saving an attacker the guesswork.

Why Fragments Like This Keep Resurfacing

Cit0day's index was broken into thousands of small parts, and collectors keep trading and reposting individual pieces long after the original service went dark. A small file like this one is easy to overlook, which is exactly why it can sit unaddressed by the people in it for years.

How a Combolist Archive Like This Operates

Cit0day compiled credentials from many separate breaches into a searchable, purchasable catalog rather than hacking any one service itself. Each part file, including this one, is a slice of that larger catalog, split up for easier distribution among people trading the credentials.

Is Your Password Buried in an Old Cit0day File?

Scan your email to check whether it appears in this fragment or elsewhere in HEROIC's records. If it does, retire that password everywhere it was reused and switch on two factor authentication for any account that offers it. It is worth running this check on both personal and work email addresses, since old archives like Cit0day rarely sort by account type.