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From: Greg Schvey <greg@schvey.com>
Date: Thu, 16 Jul 2015 08:33:48 -0700
Message-ID: <CAPYd=bAdX89R8djvVCeFBFNFx2DmTwtcAwSL-BpXA4HdXV6N1Q@mail.gmail.com>
To: Me <jimmyjack@gmail.com>
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Cc: bitcoin-dev@lists.linuxfoundation.org
Subject: Re: [bitcoin-dev] Significant losses by double-spending unconfirmed
	transactions
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Simon - tx hashes or it didn't happen

Kidding aside, would be great if you could share the confirmed and
double-spent hashes so the rest of us can dive in and learn from this.

On Thu, Jul 16, 2015 at 7:50 AM, Me via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> minrelaytxfee setting proposed in the 0.11.0 release notes
>
> my guess, he is talking about this
> https://bitcoin.org/en/glossary/minimum-relay-fee - slam dunk technique
> for doublespend
>
>
>
> 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.
>
>
> I find this useful
> https://bitcoinfees.github.io/
>
>
>
>
>
> On Jul 16, 2015, at 7:30 AM, Arne Brutschy via bitcoin-dev <
> bitcoin-dev@lists.linuxfoundation.org> wrote:
>
> 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 <http://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 <http://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 <http://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 <abrutschy@xylon.de>
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>
>
>
> _______________________________________________
> 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">Simon - tx hashes or it didn&#39;t happen<div><br></div><d=
iv>Kidding aside, would be great if you could share the confirmed and doubl=
e-spent hashes so the rest of us can dive in and learn from this.=C2=A0</di=
v></div><div class=3D"gmail_extra"><br><div class=3D"gmail_quote">On Thu, J=
ul 16, 2015 at 7:50 AM, Me via bitcoin-dev <span dir=3D"ltr">&lt;<a href=3D=
"mailto:bitcoin-dev@lists.linuxfoundation.org" target=3D"_blank">bitcoin-de=
v@lists.linuxfoundation.org</a>&gt;</span> wrote:<br><blockquote class=3D"g=
mail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-l=
eft:1ex"><div style=3D"word-wrap:break-word"><span class=3D""><div><blockqu=
ote type=3D"cite">minrelaytxfee setting proposed in the 0.11.0 release note=
s</blockquote></div></span><div>my guess, he is talking about this=C2=A0<a =
href=3D"https://bitcoin.org/en/glossary/minimum-relay-fee" target=3D"_blank=
">https://bitcoin.org/en/glossary/minimum-relay-fee</a>=C2=A0- slam dunk te=
chnique for doublespend</div><span class=3D""><div><br></div><div><br></div=
><div><br></div><div><blockquote type=3D"cite">Related: is there somewhere =
a chart that plots `estimatefee` over<br>time? Would be interesting to see =
how the fee market evolved over<br>these past weeks.</blockquote><br></div>=
</span><div>I find this useful</div><a href=3D"https://bitcoinfees.github.i=
o/" target=3D"_blank">https://bitcoinfees.github.io/</a><div><div class=3D"=
h5"><div><br></div><div><br></div><div><br></div><div><br></div><div><br><d=
iv><blockquote type=3D"cite"><div>On Jul 16, 2015, at 7:30 AM, Arne Brutsch=
y via bitcoin-dev &lt;<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.o=
rg" target=3D"_blank">bitcoin-dev@lists.linuxfoundation.org</a>&gt; wrote:<=
/div><br><div><div>Hello,<br><br>What are these pre- and post-Hearn-relay d=
rop rules you are speaking<br>about? Can anybody shed some light on this? (=
I am aware of the<br>minrelaytxfee setting proposed in the 0.11.0 release n=
otes, I just<br>don&#39;t see what this has to do with Mike Hearn, BitcoinX=
T, and whether<br>there&#39;s a code change related to this that I missed).=
<br><br>Related: is there somewhere a chart that plots `estimatefee` over<b=
r>time? Would be interesting to see how the fee market evolved over<br>thes=
e past weeks.<br><br>Regards<br>Arne<br><br>On 15/07/15 05:29, simongreen--=
- via bitcoin-dev wrote:<br><blockquote type=3D"cite">With my black hat on =
I recently performed numerous profitable <br>double-spend attacks against z=
eroconf accepting fools. With my<br>white hat on, I&#39;m warning everyone.=
 The strategy is simple:<br><br>tx1: To merchant, but dust/low-fee/reused-a=
ddress/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<br>wi=
thout triggering spam protections. (loltasticly a Mike Hearn<br>Bitcoin XT =
node was used to relay the double-spends)<br><br>Example success story: tx1=
 paying <a href=3D"http://shapeshift.io" target=3D"_blank">Shapeshift.io</a=
> with 6uBTC output<br>is not dust under post-Hearn-relay-drop rules, but i=
s dust under <br>pre-Hearn-relay-drop rules, followed by tx2 w/o the output=
 and not <br>paying <a href=3D"http://shapeshift.io" target=3D"_blank">Shap=
eshift.io</a>. F2Pool/Eligius/BTCChina/AntPool etc. are all <br>miners who =
have reverted Hearn&#39;s 10x relay fee drop as recommended<br>by v0.11.0 r=
elease notes and accept these double-spends.<br><a href=3D"http://shapeshif=
t.io" target=3D"_blank">Shapeshift.io</a> lost ~3 BTC this week in multiple=
 txs. (they&#39;re no<br>longer accepting zeroconf)<br><br>Example success =
story #2: tx1 with post-Hearn-relay drop fee,<br>followed by tx2 with highe=
r fee. Such stupidly low fee txs just<br>don&#39;t get mined, so wait for a=
 miner to mine tx2. Bought a silly<br>amount of reddit gold off Coinbase th=
is way among other things. I&#39;m<br>surprised that reddit didn&#39;t canc=
el the &quot;fools-gold&quot; after tx<br>reversal. (did Coinbase guarantee=
 those txs?) Also found multiple<br>Bitcoin ATMs vulnerable to this attack.=
 (but simulated attack with<br>tx2s still paying ATM because didn&#39;t wan=
t to go to trouble of good<br>phys opsec)<br><br>Shoutouts to BitPay who di=
d things right and notified merchant<br>properly when tx was reversed.<br><=
br>In summary, every target depending on zeroconf vulnerable and lost <br>s=
ignificant sums of money to totally trivial attacks with high <br>probabili=
ty. No need for RBF to do this, just normal variations in<br>miner policy. =
Shapeshift claims to use Super Sophisticated Network<br>Sybil Attacking Mon=
itoring from Blockcypher, but relay nodes !=3D<br>miner policy.<br><br>Cons=
ider yourself warned! My hat is whiter than most, and my skills<br>not part=
icularly good.<br><br>What to do? Users: Listen to the experts and stop rel=
ying on<br>zeroconf. Black hats: Profit!<br><br>___________________________=
____________________ bitcoin-dev mailing<br>list <a href=3D"mailto:bitcoin-=
dev@lists.linuxfoundation.org" target=3D"_blank">bitcoin-dev@lists.linuxfou=
ndation.org</a> <br><a href=3D"https://lists.linuxfoundation.org/mailman/li=
stinfo/bitcoin-dev" target=3D"_blank">https://lists.linuxfoundation.org/mai=
lman/listinfo/bitcoin-dev</a><br></blockquote><br>-- <br>Arne Brutschy &lt;=
<a href=3D"mailto:abrutschy@xylon.de" target=3D"_blank">abrutschy@xylon.de<=
/a>&gt;<br>_______________________________________________<br>bitcoin-dev m=
ailing list<br><a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" tar=
get=3D"_blank">bitcoin-dev@lists.linuxfoundation.org</a><br><a href=3D"http=
s://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev" target=3D"_blan=
k">https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev</a><br></=
div></div></blockquote></div><br></div></div></div></div><br>______________=
_________________________________<br>
bitcoin-dev mailing list<br>
<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org">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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