Many of the "free movie" networks are linked to ad networks that employ tracking scripts. These scripts can monitor user behavior across the web, collecting data on browsing habits to build profiles for targeted advertising. In worse cases, malicious scripts can intercept login credentials or financial information.
Alternatives to Piracy: Legal and Safe Ways to Watch Content world4u free org
For a safer and legal experience, it is highly recommended to use authorized streaming services that support the original creators: Many of the "free movie" networks are linked