Intermediate spoofing is capable of converting receiver's tracking loop from locking on genuine signal to spoofing signal without disturbing normal working state. This kind of attack requires precise target information, which is difficult to meet in actual attack scenario. In order to improve the feasibility of intermediate spoofing, factors affecting intermediate spoofing such as power, carrier frequency and code phase will be evaluated through theoretical analysis combined with experimental verification. Besides, we will analyze the reasons for loss of lock in intermediate spoofing. Based on the above analysis, we developed an intermediate spoofing attack device and successfully perform wireless spoofing attack against commercial u-blox receiver without knowing its accurate information.