[arunc]

Why was Jenkins running on a production server?

[deepwell]

it was not, read again

[Perceptes]

But it does seem to be the case that the same SSH key pair that was used to access Jenkins also provided access to the production infrastructure. Unless I'm misunderstanding the nature of the attack.

[zigara]

It seems the issue was developers using SSH agent forwarding which was abused to access the production environment.