Dive into the Cloud: Unveiling the (Ab)Usage of Serverless Cloud Function in the Wild

Serverless cloud functions transfer server management responsibilities to service providers, offering scalability and cost-efficiency. This convenience not only facilitates normal activities but also raises abuse concerns. So far, public understanding of real-world cloud functions remains limited. To fill this gap, we conducted an in-depth measurement study to uncover their practical usage and abuse. Through empirical analysis of nine leading providers (e.g., AWS, Tencent), we identified 531,089 function domains from a passive DNS dataset spanning April 2022 to March 2024. We first investigated the usage status of serverless cloud functions, showing the different practices between providers. Additionally, based on active requests to these functions, we pointed out privacy risks of unauthorized access and identified four abuse types, including covert C2 communication, hosting malicious websites, promoting illicit services, and abusing egress nodes as IP proxies. Alarmingly, 4.89% of cloud functions are being abused, with over 614k invocations recorded. Only four abused functions were flagged by existing threat intelligence systems, indicating critical gaps in security monitoring for serverless environments. Our work offers insights into the serverless cloud ecosystem and provides recommendations for better management. With responsible disclosure, we hope to raise awareness and improve protective measures against abuses among cloud function providers.