https://nostr.ae https://nostr.ae/npub1pwd0zptc6gwp9sah20h0f4qhpdfkyzc2p078zvm66vzea8pkc4jstdck4f https://nostr.ae/nevent1qqsvtq3tq287v5aju9le6mj9cxqq4dseypvz36zjxwnkclkvxxc8pvqzyq9e4ug90rfpcykrkaf7aax5zu94xcstpg9lcufn0tfst85uxmzk2y28nst In reply to <a href='/nevent1qqsgeldka4nku558tnfnvr6w8w0a32gj2zq22e5546g68hhmtffwnlqgh32hh'>nevent1q…32hh</a><br/>_________________________<br/><br/>📅 Original date posted:2015-07-15<br/>📝 Original message:With my black hat on I recently performed numerous profitable <br/>double-spend attacks against zeroconf accepting fools. With my white hat <br/>on, I&#39;m warning everyone. The strategy is simple:<br/><br/>tx1: To merchant, but dust/low-fee/reused-address/large-size/etc. <br/>anything that miners don&#39;t always accept.<br/><br/>tx2: After merchant gives up valuable thing in return, normal tx without <br/>triggering spam protections. (loltasticly a Mike Hearn Bitcoin XT node <br/>was used to relay the double-spends)<br/><br/>Example success story: tx1 paying Shapeshift.io with 6uBTC output is not <br/>dust under post-Hearn-relay-drop rules, but is dust under <br/>pre-Hearn-relay-drop rules, followed by tx2 w/o the output and not <br/>paying Shapeshift.io. F2Pool/Eligius/BTCChina/AntPool etc. are all <br/>miners who have reverted Hearn&#39;s 10x relay fee drop as recommended by <br/>v0.11.0 release notes and accept these double-spends. Shapeshift.io lost <br/>~3 BTC this week in multiple txs. (they&#39;re no longer accepting zeroconf)<br/><br/>Example success story #2: tx1 with post-Hearn-relay drop fee, followed <br/>by tx2 with higher fee. Such stupidly low fee txs just don&#39;t get mined, <br/>so wait for a miner to mine tx2. Bought a silly amount of reddit gold <br/>off Coinbase this way among other things. I&#39;m surprised that reddit <br/>didn&#39;t cancel the &#34;fools-gold&#34; after tx reversal. (did Coinbase <br/>guarantee those txs?) Also found multiple Bitcoin ATMs vulnerable to <br/>this attack. (but simulated attack with tx2s still paying ATM because <br/>didn&#39;t want to go to trouble of good phys opsec)<br/><br/>Shoutouts to BitPay who did things right and notified merchant properly <br/>when tx was reversed.<br/><br/>In summary, every target depending on zeroconf vulnerable and lost <br/>significant sums of money to totally trivial attacks with high <br/>probability. No need for RBF to do this, just normal variations in miner <br/>policy. Shapeshift claims to use Super Sophisticated Network Sybil <br/>Attacking Monitoring from Blockcypher, but relay nodes != miner policy.<br/><br/>Consider yourself warned! My hat is whiter than most, and my skills not <br/>particularly good.<br/><br/>What to do? Users: Listen to the experts and stop relying on zeroconf. <br/>Black hats: Profit! 2023-06-07T17:42:19+02:00