Combine sugar and water in a medium saucepan; cook over medium heat 5 minutes or until sugar dissolves, stirring constantly. Remove from heat, and cool completely.
Place cranberries in a food processor; process 2 minutes or until finely chopped. Combine sugar mixture and cranberries in a large bowl; stir in vodka.
Pour the vodka mixture into clean jars; secure with lids. Let stand 3 weeks in a cool, dark place, shaking every other day.
Strain the cranberry mixture through a cheesecloth-lined sieve into a bowl, and discard solids. Carefully pour liqueur into clean bottles or jars.
Note: Liqueur can be stored refrigerated or at room temperature for up to a year.