A Korean based group, Shincheonji “New Heaven and New Earth”, is a cult that is infiltrating churches.
Their leader is called God's advocate, the Promised Pastor. Shinchonji teaching documents seen by The Telegraph instructs these “maintainers” to “arouse curiosity” of newcomers and “try to be close to each other until the student relies on you fully”. They are told to “take notes of the conversation with the student” and report back to the group leader. More info: https://www.religionnewsblog.com/36653/shinchonji
An article entitled "On a mission from God: South Korea's many cults" describes the explosion of Korean-based cultic groups. "The world's 11th-largest economy is technologically advanced but has a history of cult organisations and charismatic religious leaders, some of whom have amassed enormous wealth and influence. Here are some groups that have previously attracted controversy or had brushes with the law."