Currently, there are many tools that modify the program code of the compiled protected modules. The authors of the considered tools do not publish technique of embedding their protection system and any proofs of their tools' algorithm correctness. This article describes the technique of program module modification with algorithm preservation for the subsequent embedding a protection system. The article suggests the verification technique for automated test of modification correctness and describes developed verification system based on this technique. The results of the work are the technique of program module modification and the verification tool for testing its correctness.