Successfully complete the indicated task in Multiplayer mode to unlock the corresponding skin:

Spy (second skin): Achieve the "Recruit" rank (with a general average higher that 1%)
Spy (third skin): Achieve the "Special Agent" rank (with a general average higher than 45%)
Uspilon Forces (second skin): Achieve the "Field Agent" rank (with a general average higher than 20%)
Uspilon Forces (third skin): Achieve the "Commander" rank (with a general average higher than 95%)