Same here, my phone was running perfectly until two weeks ago, sucked out 400Mb on data plan and i received sms from phone company, strange but i checked and all data shown by the phone also same as the phone company data.
so it is not just in the data log, however i installed three different versions of CM 10.1 and 10.2 no luck, (maybe this is a new bog or related to what you guys are discussing)
later i start looking and found out it is a google services loading data, bug is been discussed in many other place on XDA, android police but no luck to find help from CM team. no posts or comments.
lot of XDA forum mention that it is not related with ROM but more to the google OTA which is keep trying to download itself again and again, once it finish it has some issue installing it, so it will go and download again.
I then installed Miui and face the same problem, in past three hours 87 MB data is done on wifi (on miui it shows under gmail)
hope some one can help us,
Oh almost forgot i have also try FOTAKill app, some user are reporting it is working for them, but it is not working for maguro, i tried it both ways, placing the app in system app folder and then wiping the cache from CWM and also by flashing the zip file. both didn't help.
anyone know how to stop OTA update on the CM10.2 Maguro.
please help, i spend most of my time on the road and without data connection i am really stuck,
temporary fix is stop background data, but then email's don't come through and location is messed up and viber and whats app also don't show new messages unless you open the app and wait.
PLEASE PLEASE HELP