How to root? !. activate your wifi in your mobile and go to this site towelroot.com a

[PhoneWar]

How to root? !. activate your wifi in your mobile and go to this site towelroot.com and download tr.apk to your mobile and install to your mobile
2.Go to towelroot icon tap "make it rain" to install
3.Type *#9090# and choose DM\DUM over HS-USB.
4. Reboot phone.
5. Connect USB cable, install drivers.
6. Select diagnostic port in port settings and check new security
7. Press "Unlock" button.

Here's the logs......

Selected model: I337
Selected port: COM18 SAMSUNG Mobile USB Serial Port
Selected port speed: 115200
Searching ADB device...
Please, allow USB debugging on phone... OK
Reading phone info...
Model: SAMSUNG-SGH-I337
Android version: 4.4.2
Product code: SGH-I337ZWAATT
Phone version: I337UCUFNC1
PDA version: I337UCUFNC1
CSC version: I337ATTFNC1
IMEI: 356565053131xxx
Phone S/N: R31D516DZ5T
Checking Super user right... true
Backuping MMCBLK... OK
Checking phone at COM18
Backuping NVM... OK
Writing data to phone... OK
Rebooting phone... OK
Waiting phone...
Please, allow USB debugging on phone...
Please, allow USB debugging on phone... OK
Bypass MSL... OK
Unlocking... OK
Checking phone at COM18
Restoring NVM... OK
Reseting... OK
Unlock done
Done with Samsung Tool v.18.1
Done with Samsung Tool v.18.1