What Is a Combolist? File 17.10_18.21_87 Shows 3.7 Million Reasons

If you've never heard the term combolist before, file 17.10_18.21_87 is a good, if unfortunate, example of one. Released in October 2024, it contains 3,699,449 email and password pairs bundled together into a single downloadable file.

Why This Is Dangerous

A combolist is dangerous because it strips away all the effort normally required to breach an account. Instead of guessing or cracking anything, an attacker just needs the file itself, then can feed all 3,699,449 pairs into automated software that quietly tries each one against popular websites.

What Was Exposed

• Email or username entries collected from various sources
• Matching passwords stored as plain, readable text
• Website addresses showing where each credential pair originated

Why This Matters

Understanding what a combolist actually is matters because it changes how seriously people take these leaks. This isn't some abstract technical term, it's a real file with 3,699,449 working sets of someone's actual login information, and thier account could be one of them without ever knowing a breach even occured.

How Combolists Work

The word itself comes from combining combo and list, referring to the pairing of a username or email with its password. These lists get built by merging data from stealer malware infections, old breach dumps, and other sources, then cleaning duplicates before distributing the finished product, exactly like file 17.10_18.21_87.

Check If You Are Affected

Now that you know what a combolist is, check whether you are part of one. HEROIC's free scanner searches more than 400 billion (400B+) leaked records, including this exact file. If your email shows up, change that password right away and avoid reusing it anywhere else.