Your Data May Already Be Exposed. The 355 Combolist Just Surfaced.

HEROIC analysts identified a combolist file circulating on Telegram named “355.” The file surfaced on April 3, 2026 and contains 9,788 records pairing login credentials with plaintext passwords, along with the URLs of the sites each login was meant to unlock. The file is labeled only with a number, a common shorthand uploaders use to track batches without revealing where the data originated.

Why This Combolist Is Dangerous

Even a plainly labeled file like this one carries the same risk as a named breach. Because every password in this file is stored in plaintext, anyone who downloads the list can read and use each credential immediately, with no cracking or decrypting required. Combined with the target URLs included in the file, an attacker does not need to guess where to try a stolen login. The file tells them exactly where to go.

What Was Exposed

• Email addresses tied to the accounts in this file, usable to identify and target victims directly.
• Plaintext passwords, stored and shared with no encryption, meaning anyone who obtains the file can read them instantly.
• URLs showing exactly which site or service each credential pair unlocks, making it trivial for an attacker to know where to try each login.

Why This Matters for the People in It

Nearly 9,800 people had their login details packaged into a single file that anyone on the channel could download. The core risk with any combolist is credential stuffing: automated tools that take every email and password pair and try it against dozens of popular websites in seconds. If you have ever reused a password across more than one account, and most people have, a single leaked line here can lead to a compromised email account, drained loyalty points, hijacked social media, or worse.

How the '355' Combolist Fits the Bigger Picture

Unlike a breach at a single company, a combolist is a curated file that pulls email and password pairs together from multiple prior leaks, stealer logs, and phishing campaigns. Telegram channels dedicated to credential trading are the main distribution point, where uploaders package these lists by size, freshness, or target (a bank, a shopping site, a webmail provider) to make them more attractive to buyers.

The danger is automation. Criminals feed combolists into bots that test every pair against dozens of popular websites in minutes, a technique known as credential stuffing. Because so many people reuse the same password across accounts, one exposed line can unlock an entire digital identity: email, banking, social media, and more.

Check If You Are Affected

The safest move after any exposure like this is to find out quickly whether your own information is part of it. HEROIC's free breach scanner checks your email address against a database of more than 400 billion breached and leaked records, including combolists, stealer logs, and other underground dumps like this one. If a match turns up, change the affected password immediately, enable multi-factor authentication wherever it is offered, and avoid reusing that password anywhere else.