Excessive data usage with nothing running

[lovestruck]

Using El Capitan on MacBook Pro... last few days my bandwidth usage has skyrocketed ..have turned all apps off but still being used fast.

Nothing is showing in network tab of activity monitor except the data usage going up and up.

Have turned all auto updates off...Java off..Bluetooth off..

Wworried might have malware auto connecting to something..is this possible?

Connect via 3G dongle with limited data usage so need to find what it is and stop it!

 

[JohnDS]

Download and run Little Snitch: https://www.obdev.at/products/littlesnitch/index.html

 

[Weaselboy]

Is this data download or upload? Reboot then go back to Activity Monitor and sort by the sent or rcvd column and it will show you what is using data.

 

[JohnDS]

Are you using Dropbox, perhaps? Is iCloud synching photos or music? Do you have iTunes turned off?