In the past decade, extra-institutional file-sharing and homework-help websites have gone from being small-scale operations to large corporate businesses. File-sharing and homework-help websites threaten academic integrity when students use assessment work sourced from these sites as if it were their own. However, little is known about how students use these websites, what motivates students' use, and whether students are aware of the risks of using these sites. In an international survey of 1000 students, nearly half had heard of, or used, file-sharing and homework-help websites, and 377 completed a longer follow-up survey. We also undertook qualitative analysis of social media posts related to file-sharing and homework-help websites. Students indicate that they used the websites to obtain material to study for and/or complete assessments, and they exchanged assessment and study materials for altruistic reasons as well as for personal benefit. Students were mostly aware of academic integrity risks in using the websites but were typically unaware of their own institutions' position or policies regarding the use of these sites. It is recommended that higher education institutions develop policies and educate students regarding unaffiliated file-sharing and homework-help websites to promote academic integrity.