Practical security for multi-user web application databases

Abstract

Online web applications are continuously vulnerable to attacks on their users' data. Outside adversaries can gain unauthorized access by exploiting unknown vulnerabilities; curious or malicious database administrators can examine or alter the data in situ. Multiple Principal CryptDB protects against attacks on web application servers. By chaining encryption keys to user passwords, an attacker gaining access to decrypted data through issuing arbitrary queries to the database through CryptDB cannot access data belonging to offline users. A logging system and distributed key storage for CryptDB constrain the pool of possibly compromised data after an attack. Multiple Principal CryptDB can be used to secure the data of six web applications examined, with 2-8 lines of altered source code and 15-111 annotations added to the schema. On the phpBB web forum application, Multiple Principal CryptDB reduces throughput by only 14.5%, with 24 sensitive fields encrypted, and adds less than 26ms of latency to each individual query.