to use an ally's resources or territory as a pretext or means to attack a common enemy

他们表面上是技术合作，实际上是想假道伐虢，利用对方的渠道打压竞争对手。

to obtain safe passage through a neutral territory to conquer a target state (historically the State of Guo)

晋国利用假道伐虢的计谋，先灭了虢国，回程时又顺手灭了借路的虞国。