Easy Live

The Credit Card Fraudster

20 points

649 Solves

Programming

ebouteillon

Community Rating: 4.71 / 5

Headline

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

I just arrested someone who is probably the most wanted credit card fraudster in Europe. She is a smart cybercriminal, always a step ahead INTERPOL and she kept unnoticed for years by never buying online, but buying goods with a different card every time and in different stores. My cyber-analysts found out after collecting all evidences she hacked into one the largest payment provider in Europe, reverse-engineered the software present on the server and partly corrupted the card number validation code to accept all her payments. The change enables acceptance of any transaction with a card number multiple of 123457 and the Luhn check digit is valid.

I caught her because every year she bought a bouquet of flowers next to the same cemetery. While handcuffing her at the flower shop's exit, she said the flowers were for her lost father and today it is his death anniversary. She broke down in tears and she did some steps and threw something in the sewers. My female colleague conducted a search on her, but she couldn't find the card she used, only the receipt.

The little flower shop
======================

European Express Debit
Card Number: 543210******1234
SALE

Please debit my account
Amount: 25.00€

Can you help me to recover the card number so that I can confirm with the flower merchant's bank the card number was used in that shop and is fraudulent?

Hints:

1/ Luhn_algorithm

2/ Flag format is CTFlearn{card_number}

First 10 Solvers

Rank Username
1 mamimi1773
2 heyzec
3 ill_advisor
4 Ragloph
5 Rivit
Rank Username
6 SARVAR
7 gray_cat
8 becktech
9 Seppukki
10 LiorBaruch

Comments

    • SypHr

      Protected 0.0

      [REDACTED] This comment is only shown to users who have solved this challenge.

    • Franck21

      Protected 1

      [REDACTED] This comment is only shown to users who have solved this challenge.

    • regex7

      Protected 0.0

      [REDACTED] This comment is only shown to users who have solved this challenge.

    • N3PH1L4X

      Protected 0.0

      [REDACTED] This comment is only shown to users who have solved this challenge.