1 INTRODUCTION  

2 BACKGROUND AND PRELIMINARIES  

3 A NOTE ON BLACK MARKET SERVICES  

4 COMPROMISED ONLINE PLATFORMS  

5 TYPES OF COLLUSIVE ACTIVITIES  

6 PROGRESS IN COLLUSIVE ENTITY DETECTION  

7 ANNOTATION GUIDELINES, DATASETS, APPLICATIONS AND EVALUATION METRICS  

8 OPEN PROBLEMS  

9 CONCLUSION AND OPEN CHALLENGES