From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id B7810323 for ; Thu, 16 Jul 2015 14:38:06 +0000 (UTC) X-Greylist: delayed 00:07:46 by SQLgrey-1.7.6 Received: from mail.xylon.de (ds87-230-39-135.dedicated.hosteurope.de [87.230.39.135]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id AC91D25C for ; Thu, 16 Jul 2015 14:38:05 +0000 (UTC) Received: from mail.xylon.de (localhost [127.0.0.1]) by mail.xylon.de (Postfix) with ESMTP id 2648E8A0051; Thu, 16 Jul 2015 16:30:17 +0200 (CEST) Received: from [192.168.178.47] (dslb-178-004-222-124.178.004.pools.vodafone-ip.de [178.4.222.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.xylon.de (Postfix) with ESMTPSA id E0C498A0018; Thu, 16 Jul 2015 16:30:16 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=xylon.de; s=alpha; t=1437057017; bh=YABaFSLhWlaMG8UHw9OdSJGJl8Arm66EYYOFrc8qRAA=; h=Date:From:To:CC:Subject:References:In-Reply-To; b=GnDtNSiO1Dul1ZPrKKvKsYbxSXcgkfRTM8yFfNu636SepuqM7MtLHg4JzUTX5p4Bw dyO0yMazE35l4Kd5hv3OI+6kM1KvuvrcgE9YnyV6QW2EikOVxweTO9hCTkjuz/ggCp VEq5Ot5qRVSW4mdFlzM0S6azV6o1IcQPDFDtVkEI= Message-ID: <55A7BFF7.2050608@xylon.de> Date: Thu, 16 Jul 2015 16:30:15 +0200 From: Arne Brutschy User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: bitcoin-dev@lists.linuxfoundation.org References: <24662b038abc45da7f3990e12a649b8a@airmail.cc> In-Reply-To: <24662b038abc45da7f3990e12a649b8a@airmail.cc> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-AV-Checked: ClamAV using ClamSMTP X-Spam-Status: No, score=-2.0 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Subject: Re: [bitcoin-dev] Significant losses by double-spending unconfirmed transactions X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Development Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 16 Jul 2015 14:38:06 -0000 Hello, What are these pre- and post-Hearn-relay drop rules you are speaking about? Can anybody shed some light on this? (I am aware of the minrelaytxfee setting proposed in the 0.11.0 release notes, I just don't see what this has to do with Mike Hearn, BitcoinXT, and whether there's a code change related to this that I missed). Related: is there somewhere a chart that plots `estimatefee` over time? Would be interesting to see how the fee market evolved over these past weeks. Regards Arne On 15/07/15 05:29, simongreen--- via bitcoin-dev wrote: > With my black hat on I recently performed numerous profitable > double-spend attacks against zeroconf accepting fools. With my > white hat on, I'm warning everyone. The strategy is simple: > > tx1: To merchant, but dust/low-fee/reused-address/large-size/etc. > anything that miners don't always accept. > > tx2: After merchant gives up valuable thing in return, normal tx > without triggering spam protections. (loltasticly a Mike Hearn > Bitcoin XT node was used to relay the double-spends) > > Example success story: tx1 paying Shapeshift.io with 6uBTC output > is not dust under post-Hearn-relay-drop rules, but is dust under > pre-Hearn-relay-drop rules, followed by tx2 w/o the output and not > paying Shapeshift.io. F2Pool/Eligius/BTCChina/AntPool etc. are all > miners who have reverted Hearn's 10x relay fee drop as recommended > by v0.11.0 release notes and accept these double-spends. > Shapeshift.io lost ~3 BTC this week in multiple txs. (they're no > longer accepting zeroconf) > > Example success story #2: tx1 with post-Hearn-relay drop fee, > followed by tx2 with higher fee. Such stupidly low fee txs just > don't get mined, so wait for a miner to mine tx2. Bought a silly > amount of reddit gold off Coinbase this way among other things. I'm > surprised that reddit didn't cancel the "fools-gold" after tx > reversal. (did Coinbase guarantee those txs?) Also found multiple > Bitcoin ATMs vulnerable to this attack. (but simulated attack with > tx2s still paying ATM because didn't want to go to trouble of good > phys opsec) > > Shoutouts to BitPay who did things right and notified merchant > properly when tx was reversed. > > In summary, every target depending on zeroconf vulnerable and lost > significant sums of money to totally trivial attacks with high > probability. No need for RBF to do this, just normal variations in > miner policy. Shapeshift claims to use Super Sophisticated Network > Sybil Attacking Monitoring from Blockcypher, but relay nodes != > miner policy. > > Consider yourself warned! My hat is whiter than most, and my skills > not particularly good. > > What to do? Users: Listen to the experts and stop relying on > zeroconf. Black hats: Profit! > > _______________________________________________ bitcoin-dev mailing > list bitcoin-dev@lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev -- Arne Brutschy