Re:How I got a Root Shell on a Credit Card Terminal
by qmarchi on Sunday June 01, 2025 @11:49AM
(#44151743)
Disc: Former Visa Employee
Generally, these devices will use the mp1 to do all of the cryptographic operations around the devices.
The biggest part of this is the keys defined between the terminal and the acceptance gateway (something like CyberSource or Authorize.net).
When the temper protection is tripped the keys that are used are immediately dropped from RAM and you can't recover them, they have to manually be input into the device again to reset the tamper protection.
(Side Note: keys are specific to a merchant. If you're able to extract them, it limits the blowback.)
Generally, these devices will use the mp1 to do all of the cryptographic operations around the devices.
The biggest part of this is the keys defined between the terminal and the acceptance gateway (something like CyberSource or Authorize.net).
When the temper protection is tripped the keys that are used are immediately dropped from RAM and you can't recover them, they have to manually be input into the device again to reset the tamper protection.
(Side Note: keys are specific to a merchant. If you're able to extract them, it limits the blowback.)