Carleton University's IT department says its network may have been compromised.
Computing and Communications Services says it has detected an external hacking attempt, and any Windows system accessible from the main network may have been affected.
It's warning people may end up running into ransomware messages demanding money.
CCS is telling users to ignore them and contact the help desk.
Earlier in the day, the IT department said it had noticed a number of network issues affecting email, access to network drives and other services.