McKinsey requires hiring an external pen-testing company to launch even to a small group of coworkers.
I can forgive this kind of mistake on the part of the Lilli devs. A lot of things have to fail for an "agentic" security company to even find a public endpoint, much less start exploiting it.
That being said, the mistakes in here are brutal. Seems like close to 0 authz. Based on very outdated knowledge, my guess is a Sr. Partner pulled some strings to get Lilli to be publicly available. By that time, much/most/all of the original Lilli team had "rolled off" (gone to client projects) as McKinsey HEAVILY punishes working on internal projects.
So Lilli likely was staffed by people who couldn't get staffed elsewhere, didn't know the code, and didn't care. Internal work, for better or worse, is basically a half day.
This is a failure of McKinsey's culture around technology.