<blockquote>
  <p>On July 29 2010, it was discovered that block 71036 contained several transactions with a ton of OP_CHECKSIG commands. There should only ever be one such command. This caused every node to do extra unnecessary work, and it could have been used as a denial-of-service attack. A new version of Bitcoin was quickly released. The new version did not cause a fork on the main network, though it did cause one on the test network (where someone had played around with the attack more).</p>
</blockquote>

<p><a href="https://en.bitcoin.it/wiki/Incidents#OP_CHECKSIG_abuse">https://en.bitcoin.it/wiki/Incidents#OP_CHECKSIG_abuse</a></p>

CC BY-SA 3.0
2011-10-05T17:37:26.217Z
nice link, really worth reading
Mascarpone
CC BY-SA 3.0
2011-10-05T15:02:04.950Z
2011-10-05T15:02:04.950Z
lemonginger
<p>What happened to this transaction?</p>

<p>Can someone explain it?</p>

<p><a href="http://blockexplorer.com/t/9eHTFRi3Qq" rel="nofollow">http://blockexplorer.com/t/9eHTFRi3Qq</a></p>

<blockchain><blockchain-fork><weaknesses>
Strange transaction (block 71036)
Mascarpone
# Strange transaction (block 71036)

(Asked by: username_0 on 2011-10-05)

What happened to this transaction?

Can someone explain it?

<http://blockexplorer.com/t/9eHTFRi3Qq>

**Tags:** blockchain, blockchain-fork, weaknesses


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## 1 answers

### Answer by username_1 on 2011-10-05. Score: 11 | Accepted answer

> On July 29 2010, it was discovered that block 71036 contained several transactions with a ton of OP\_CHECKSIG commands. There should only ever be one such command. This caused every node to do extra unnecessary work, and it could have been used as a denial-of-service attack. A new version of Bitcoin was quickly released. The new version did not cause a fork on the main network, though it did cause one on the test network (where someone had played around with the attack more).

<https://en.bitcoin.it/wiki/Incidents#OP_CHECKSIG_abuse>

> **Comments:**
> **username_0**: nice link, really worth reading  

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