2017-09-15 20:19:19 +00:00
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---
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title: The Bitcoin Piñata
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2017-09-17 18:52:58 +00:00
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abstract: 
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2017-09-15 20:19:19 +00:00
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---
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2017-09-17 18:52:58 +00:00
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2017-09-17 13:13:28 +00:00
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The [Bitcoin Piñata](http://ownme.ipredator.se) is a unikernel which serves as
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bug bounty system to test TLS and the underlying implementations. Its
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communication endpoints are a website describing the setup, and both a TLS
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client and a TLS server listening on a port. The total size, including TLS,
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X.509, TCP/IP, of the virtual machine image is 4MB, which is less than 4% of a
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comparable system using a Linux kernel and OpenSSL.
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When a TLS handshake is successfully completed with mutual authentication, the
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Piñata transmits the private key to a bitcoin wallet which is filled with ~10BTC
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2017-11-09 22:30:24 +00:00
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(~60 000 EUR).
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2017-09-17 13:13:28 +00:00
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On startup, the Piñata generates its certificate authority on the fly, including
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certificates and private keys. This means that only the Piñata itself contains
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2017-09-17 14:00:44 +00:00
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private keys which can authenticate successfully, and an attacker has to find
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2017-09-17 13:13:28 +00:00
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an exploitable flaw in any software layer (OCaml runtime, virtual network
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2017-09-17 14:00:44 +00:00
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device, TCP/IP stack, TLS library, X.509 validation, or elsewhere) to complete the challenge.
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2017-09-17 13:13:28 +00:00
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2017-09-17 14:00:44 +00:00
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The Piñata is online since February 2015, and even though thousands of unique IP
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2017-09-17 13:13:28 +00:00
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addresses initiated connections, the wallet still contains the 10 BTC.
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By using a Bitcoin wallet, the Piñata is a transparent bug bounty. Everybody
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can observe (by looking into the Bitcoin blockchain) whether it has been
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compromised and the money has been transferred to another wallet. It is also
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self-serving: when an attacker discovers a flaw, they don't need to fill out
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any forms to retrieve the bounty, instead they can take the wallet, without any
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questions asked.
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