Twitter
Facebook
LinkedIn
Google+
YouTubeusenix conference policies
Website Maintenance Alert
Due to scheduled maintenance on Wednesday, October 16, from 10:30 am to 4:30 pm Pacific Daylight Time (UTC -7), parts of the USENIX website (e.g., conference registration, user account changes) may not be available. We apologize for the inconvenience.
If you are trying to register for LISA19, please complete your registration before or after this time period.
Fixing Races for Fun and Profit: How to Abuse atime
Dean and Hu proposed a probabilistic countermeasure to the classic access(2)/open(2) TOCTTOU race condition in privileged Unix programs [4]. In this paper, we describe an attack that succeeds with very high probability against their countermeasure. We then consider a stronger randomized variant of their defense and show that it, too, is broken. We conclude that access(2) must never be used in privileged Unix programs. The tools we develop can be used to attack other filesystem races, underscoring the importance of avoiding such races in secure software.