BelkaCTF #6: Bogus Bill

BelkaCTF #6 is over, the gang of money forgers is all caught. Thank you for being a part of this! Congratulations to the winners:
Student track: its5Q, belkakaka, kiwi
Professional track: sinsa, sm233, teo4n6

đź“„ BelkaCTF #6: Bogus Bill write-up

—Chief, their bill quality shows some real delicate work.

—Agreed, but what's the takeaway?

—They had insider info.

—Hinting at technical details of the bill validator?

I added a touch of flattery to my voice.

— You're the man for a reason, Chief!

Hard
691
Mole
Solved 11 times

Who leaked the technical data on the bill validator to the gang?
Format: First name Last name

Flag:


100 100 100 127 100 208 643 40 286 357 603 438 438 315 357 579 691 829 590 50