Re: Captchas – Understanding CAPTCHA-solving services in an economic context

Marti Motoyama, Kirill Levchenko, Chris Kanich, Damon McCoy, Geoffrey M. Voelker, Stefan Savage

    Research output: Chapter in Book/Report/Conference proceedingConference contribution


    Reverse Turing tests, or CAPTCHAs, have become an ubiquitous defense used to protect open Web resources from being exploited at scale. An effective CAPTCHA resists existing mechanistic software solving, yet can be solved with high probability by a human being. In response, a robust solving ecosystem has emerged, reselling both automated solving technology and real-time human labor to bypass these protections. Thus, CAPTCHAs can increasingly be understood and evaluated in purely economic terms; the market price of a solution vs the monetizable value of the asset being protected. We examine the market-side of this question in depth, analyzing the behavior and dynamics of CAPTCHA-solving service providers, their price performance, and the underlying labor markets driving this economy.

    Original languageEnglish (US)
    Title of host publicationProceedings of the 19th USENIX Security Symposium
    PublisherUSENIX Association
    Number of pages18
    ISBN (Electronic)9781931971775
    StatePublished - 2010
    Event19th USENIX Security Symposium - Washington, United States
    Duration: Aug 11 2010Aug 13 2010

    Publication series

    NameProceedings of the 19th USENIX Security Symposium


    Conference19th USENIX Security Symposium
    Country/TerritoryUnited States

    ASJC Scopus subject areas

    • Computer Networks and Communications
    • Information Systems
    • Safety, Risk, Reliability and Quality


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