/proc/net/dev is giving wrong traffic info

I have an applet which reads /proc/net/dev and displays network up/download speed. A few days back it started showing weird things. Like, even when I'm not on the internet, the download speed stays around 52-54 kbps, while normally it tends to stay below 10 kbps. Sometimes it keeps jumping between 10kbps to 400kbps(when the system is idle). I checked the file and it was indeed showing unusual behaviour. The applet is all fine. iftop shows traffic as I expected it to be. What could be the reason? I guess the dev file provides a more basic interface to the hardware. So can it be the case that my pc is under some sort of attack?