The Relationship between BIN Numbers and 3-D Secure: How It Works

[Cloned Boy]

Educational analysis to understand online payment security.

1. What is 3-D Secure?​

3-D Secure (3DS) is an authentication protocol used to protect online payments. It is used in:

• Visa Secure (formerly Verified by Visa).
• Mastercard Identity Check.
• MirAccept (for Mir cards).

How it works:

1. The user enters card details.
2. The system checks the BIN to determine:
   • Does the card support 3DS?
   • What type of authentication is required (SMS, push notification, biometrics).
3. If required, redirects to the bank page for confirmation (entering OTP, face scanning, etc.).

2. The role of BIN in 3-D Secure​

2.1. Defining authentication rules​

• Banks set up different verification levelsfor different BINs:
  • Debit cards (4xxxxx) → More often require SMS.
  • Credit cards (5xxxxx) → May use push notifications.
  • Corporate cards → Two-factor authentication (2FA).

Example:

• BIN 4276 29 (Sberbank, debit) → Standard SMS verification.
• BIN 5536 91 (T-Bank, credit) → Push notification in the application.

2.2. Geographical features​

• BIN indicates the country of issue of the card, which affects the 3DS rules:
  • EU (PSD2): For payments > €30 SCA (Strong Customer Authentication) is mandatory.
  • USA: 3DS 1.0 (less strict checks) is more commonly used.

2.3. Dynamic Risk Management​

Payment systems analyze BIN in real time to:

• Reduce friction (don't require 3DS for small, low-risk payments).
• Block scammers: If BIN is from the "dangerous" range → mandatory authentication.

3. How do scammers try to bypass 3DS? (For protection, not for attacks!)​

1. Using BIN without 3DS:
   • Some older BINs (such as prepaid cards) may not support 3DS.
   • Protection: Banks are gradually disabling such BINs.
2. Fake 3DS pages:
   • Phishing to intercept OTP.
   • Protection: Domain verification (the real 3DS page is always on the bank's website).
3. BIN spoofing:
   • Substitution of BIN in a transaction (rare, but possible due to vulnerabilities in the merchant software).
   • Security : EMV 3-D Secure 2.0 (verifies the cryptographic signature of the BIN).

4. Example of 3DS + BIN work​

Scenario: Purchase for €100 with card BIN 5154 61 (Mastercard, Germany).

1. The store sends a request to the payment system.
2. The system checks the BIN and determines:
   • Country: Germany → SCA (PSD2) required.
   • Card type: Credit → Authentication method: Push notification.
3. The user confirms the payment in the bank's mobile application.

5. How is protection improved?​

• 3-D Secure 2.0+:
  • No redirect (authentication in the store application).
  • Device data (digital fingerprint for risk assessment).
• Removing "weak" BINs: Banks are gradually removing BINs without 3DS support from circulation.

Conclusion​

BIN and 3-D Secure are closely related:
BIN determines → Whether authentication is needed, what type and severity.
3DS protects → Even if a fraudster has learned the card number, the payment will not go through without confirmation.

For legal study:

• Experiment with a Sandbox environment (e.g. Stripe 3DS tests).
• Read Visa/Mastercard documentation on 3DS.

Want to understand how 3DS 2.0 works or how banks detect fake BINs? Ask!