Our Analysts Found the Japan Rent a Car Dump With 213K Plaintext Passwords

HEROIC analysts flagged the Japan Rent a Car breach while reviewing a cluster of database dumps tied to Japanese-language service platforms. The breach occured in August 2018 and affected approximately 213,973 accounts. What made this incident seperate from others in the same timeframe was the discovery that passwords were stored entirely in plaintext, meaning any attacker who accessed the database recieved ready-to-use credentials with no cracking required.

Plaintext Passwords: The Most Dangerous Thing in the Japan Rent a Car Leak

Unlike hashed passwords, plaintext credentials require zero effort to exploit. Attackers can take the exported email-and-password pairs directly into automated tools and attempt logins across banking portals, email providers, and corporate systems. Because many users reuse the same password across services, a single plaintext breach can cascade into dozens of account takeovers almost instantly.

What Was Exposed in the Japan Rent a Car Breach

• Email Address
• Plaintext Password

Why Car Rental Customers Face Serious Downstream Risk

Travel and rental platforms collect data from customers who are partcularly likely to use the same email-and-password combination across airline accounts, hotel loyalty programs, and personal email. Credential stuffing attacks built from this breach data can unlock accounts holding frequent flyer miles, travel credits, and stored payment methods, enabling financial fraud without any additional hacking required.

How Database Breaches Work

A database breach occurs when unauthorized access is gained to a server's backend data store, often through SQL injection, exposed administrative interfaces, or compromised credentials. The attacker extracts structured records from user tables. When the breached company stores passwords in plaintext rather than using a modern hashing algorithm, the extracted data is immediately usable with no further processing by the attacker.

Check If Your Data Was Exposed

HEROIC's free breach scanner checks your email address against more than 400 billion records, including the Japan Rent a Car database dump. Run a free scan in seconds and find out whether your credentials from this breach are circulating on the dark web right now.