Getting into top consulting firms does require one to have a background that is exciting for the firm. This often (but not always) means going to a target school, achieving high grades in your classes and having interesting extra curricular activities/work experience to talk about.
It appears that you have the target school but not a good GPA. If you want to go to consulting in this scenario, business school is definitely a good way to go about it. Consulting firms hire from there and if you are at a top 10 school your chances of making it are quite high. Of course this comes with a high price tag, but is the one with the highest probability of success.
Is it possible to get in even without this? Yes under some circumstances. At the end of the day consulting firms need people who are experts in their chosen field and bring in a wealth of knowledge. So an alternative path to consulting would be to acquire a lot of experise in a particular field you are passionate about, over a period of 4-5 years. Get recognized as a leader in this field, and then leverage that to cross over into consulting
Another easier way is to enter consulting but not as a consultant - for example you can apply to be a solutions consultant in a McKinsey solutions team or an R&I consultant. These are typically seen as less prestigious roles but you still get to work at a prestigious firm.