Security Protocols

Volume 4631 of the series Lecture Notes in Computer Science pp 162-169

Countering Automated Exploits with System Security CAPTCHAS

  • Dinan GunawardenaAffiliated withMicrosoft Research Cambridge
  • , Jacob ScottAffiliated withUC Berkley, CA
  • , Alf ZugenmaierAffiliated withDoCoMo Euro-Labs, Munich
  • , Austin DonnellyAffiliated withMicrosoft Research Cambridge

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Many users routinely log in to their system with system administrator privileges. This is especially true of home users. The advantage of this setup is that these users can do everything necessary to fulfil their tasks with the computer. The disadvantage is that every program running in the users context can make arbitrary modifications to the system. Malicious programs and scripts often take advantage of this and silently change important parameters. We propose to verify that these changes were initiated by a human by a ceremony making use of a CAPTCHA (Completely Automated Public Turing Test to Tell Computers and Humans Apart). We compare this approach with other methods of achieving the same goal, i.e. passwords, secure path and access control based on zone of origin of the code.