Ransomware
What it looks like
Files across shares and servers renamed with an unfamiliar extension. A ransom note dropped into every folder. Line-of-business applications throwing database errors, staff locked out one department at a time, and the backup console either unreachable or showing jobs that were deleted days ago.
What we do
We isolate the affected hosts and the accounts being used to move between them, work out how the attacker got in and how far they went, and check whether your backups are both intact and clean. We look for signs that data was copied out before encryption, because that changes what you have to deal with afterwards. Only once the environment is contained and persistence has been hunted down do we rebuild and restore.
What not to do
Do not reboot or reimage the affected machines, do not restore into the same network before it has been cleared, do not delete the ransom note, and do not open a conversation with the attacker before you have advice.

