From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sog-mx-4.v43.ch3.sourceforge.com ([172.29.43.194] helo=mx.sourceforge.net) by sfs-ml-1.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1T414Y-0005AF-Bg for bitcoin-development@lists.sourceforge.net; Wed, 22 Aug 2012 02:53:34 +0000 X-ACL-Warn: Received: from zinan.dashjr.org ([173.242.112.54]) by sog-mx-4.v43.ch3.sourceforge.com with esmtp (Exim 4.76) id 1T414X-0001gO-IS for bitcoin-development@lists.sourceforge.net; Wed, 22 Aug 2012 02:53:34 +0000 Received: from ishibashi.localnet (unknown [97.96.85.141]) (Authenticated sender: luke-jr) by zinan.dashjr.org (Postfix) with ESMTPSA id CE79F27A297B; Wed, 22 Aug 2012 02:53:27 +0000 (UTC) From: "Luke-Jr" To: bitcoin-development@lists.sourceforge.net Date: Wed, 22 Aug 2012 02:53:21 +0000 User-Agent: KMail/1.13.7 (Linux/3.4.5-gentoo-nestfix; KDE/4.8.3; x86_64; ; ) References: In-Reply-To: X-PGP-Key-Fingerprint: E463 A93F 5F31 17EE DE6C 7316 BD02 9424 21F4 889F X-PGP-Key-ID: BD02942421F4889F X-PGP-Keyserver: hkp://pgp.mit.edu MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message-Id: <201208220253.24822.luke@dashjr.org> X-Spam-Score: -0.1 (/) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. -0.2 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.1 AWL AWL: From: address is in the auto white-list X-Headers-End: 1T414X-0001gO-IS Subject: Re: [Bitcoin-development] Full Disclosure: CVE-2012-2459 (block merkle calculation exploit) X-BeenThere: bitcoin-development@lists.sourceforge.net X-Mailman-Version: 2.1.9 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 22 Aug 2012 02:53:34 -0000 On Wednesday, August 22, 2012 2:25:20 AM Forrest Voight wrote: > An unpatched Bitcoin installation can be permanently wedged at its > current highest block using this and the fact that Bitcoin caches > orphan blocks in a disk-backed database. To do so, the attacker must > send it a valid block (that will eventually make it into the > blockchain) made invalid by duplicating one of the transactions in a > way that preserves the Merkle root. The attacker doesn't even need to > mine their own block - instead, they can listen for a block, then > mutate it in this way, and pass it on to their peers. =46rom the mining perspective, the unpatched install might not be simply we= dged:=20 it will also follow a competing smaller blockchain. An attacker could have= =20 used this exploit against a number of large miners (say about 40% or so) an= d=20 exchanges to pull off any number of double-spend attacks until the miners=20 noticed they had been forked and fixed their bitcoind. That is, the attacke= r=20 could easily hijack as much of the miners has he wanted for his own purpose= s=20 including phony 6+ confirmation transactions. On a more subtle level, the=20 attacker could target certain blocks they wanted orphans by performing this= =20 attack on a majority of miners with the "tip" block he wanted orphaned. This vulnerability is also the reason why Eloipool (the software behind=20 Eligius, EclipseMC, TripleMining, and other pools) has attempted to produce= =20 blocks with only transaction counts that are powers of two; such blocks can= not=20 be used for an attack even against vulnerable clients. Luke