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Date: Wed, 15 Jul 2015 10:01:56 -0700
Message-ID: <CAMK47c91-4FSAWhBaGvAtDZhxWt4ZyKAOKnZO2tC4iewmfYyYA@mail.gmail.com>
From: Adrian Macneil <adrian@coinbase.com>
To: simongreen@airmail.cc
Content-Type: multipart/alternative; boundary=001a11353af687a318051aece9e6
Cc: bitcoin-dev@lists.linuxfoundation.org
Subject: Re: [bitcoin-dev] Significant losses by double-spending unconfirmed
	transactions
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> With my white hat on

> Shapeshift.io lost ~3 BTC this week in multiple txs

I assume as a self proclaimed "white hat", you contacted the relevant
companies and returned their funds? Theft is still theft, regardless of
whether you are doing it for research or not.

On Tue, Jul 14, 2015 at 8:29 PM, simongreen--- via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> 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
>
>

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<div dir=3D"ltr"><div><span style=3D"font-size:12.8000001907349px">&gt;=C2=
=A0</span><span style=3D"font-size:12.8000001907349px">With my white hat on=
</span><br></div><div><br></div>&gt;=C2=A0<span style=3D"font-size:12.80000=
01907349px">Shapeshift.io lost ~3 BTC this week in multiple txs</span><div>=
<br></div><div><div><span style=3D"font-size:12.8000001907349px">I assume a=
s a self proclaimed &quot;white hat&quot;, you contacted the relevant compa=
nies and returned their funds? Theft is still theft, regardless of whether =
you are doing it for research or not.</span></div></div></div><div class=3D=
"gmail_extra"><br><div class=3D"gmail_quote">On Tue, Jul 14, 2015 at 8:29 P=
M, simongreen--- via bitcoin-dev <span dir=3D"ltr">&lt;<a href=3D"mailto:bi=
tcoin-dev@lists.linuxfoundation.org" target=3D"_blank">bitcoin-dev@lists.li=
nuxfoundation.org</a>&gt;</span> wrote:<br><blockquote class=3D"gmail_quote=
" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">W=
ith my black hat on I recently performed numerous profitable double-spend a=
ttacks against zeroconf accepting fools. With my white hat on, I&#39;m warn=
ing everyone. The strategy is simple:<br>
<br>
tx1: To merchant, but dust/low-fee/reused-address/large-size/etc. anything =
that miners don&#39;t always accept.<br>
<br>
tx2: After merchant gives up valuable thing in return, normal tx without tr=
iggering spam protections. (loltasticly a Mike Hearn Bitcoin XT node was us=
ed to relay the double-spends)<br>
<br>
Example success story: tx1 paying Shapeshift.io with 6uBTC output is not du=
st under post-Hearn-relay-drop rules, but is dust under pre-Hearn-relay-dro=
p rules, followed by tx2 w/o the output and not paying Shapeshift.io. F2Poo=
l/Eligius/BTCChina/AntPool etc. are all miners who have reverted Hearn&#39;=
s 10x relay fee drop as recommended by v0.11.0 release notes and accept the=
se double-spends. Shapeshift.io lost ~3 BTC this week in multiple txs. (the=
y&#39;re no longer accepting zeroconf)<br>
<br>
Example success story #2: tx1 with post-Hearn-relay drop fee, followed by t=
x2 with higher fee. Such stupidly low fee txs just don&#39;t get mined, so =
wait for a miner to mine tx2. Bought a silly amount of reddit gold off Coin=
base this way among other things. I&#39;m surprised that reddit didn&#39;t =
cancel the &quot;fools-gold&quot; after tx reversal. (did Coinbase guarante=
e those txs?) Also found multiple Bitcoin ATMs vulnerable to this attack. (=
but simulated attack with tx2s still paying ATM because 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 whe=
n tx was reversed.<br>
<br>
In summary, every target depending on zeroconf vulnerable and lost signific=
ant sums of money to totally trivial attacks with high probability. No need=
 for RBF to do this, just normal variations in miner policy. Shapeshift cla=
ims to use Super Sophisticated Network Sybil Attacking Monitoring from Bloc=
kcypher, but relay nodes !=3D miner policy.<br>
<br>
Consider yourself warned! My hat is whiter than most, and my skills not par=
ticularly good.<br>
<br>
What to do? Users: Listen to the experts and stop relying on zeroconf. Blac=
k hats: Profit!<br>
<br>
_______________________________________________<br>
bitcoin-dev mailing list<br>
<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" target=3D"_blank">=
bitcoin-dev@lists.linuxfoundation.org</a><br>
<a href=3D"https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev" =
rel=3D"noreferrer" target=3D"_blank">https://lists.linuxfoundation.org/mail=
man/listinfo/bitcoin-dev</a><br>
<br>
</blockquote></div><br></div>

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