Save any data you need and consider the machine totally compromised. By that, I mean you need to consider any IPMI processor compromised as well, since these c

Save any data you need and consider the machine totally compromised. By that, I mean you need to consider any IPMI processor compromised as well, since these can be attacked (or their secrets stolen). Basically rebuild the machine from as low a level as you can. Depending on the brand of server hardware, you may need physical access.