user1475: Dan Kaminsky said that he spent 4 months trying to hack "bitcoin" but failed.
Besides trying to find vulnerabilities in double-spending and 51% attack, what other hacks would a hacker try to achieve?
Surely an established hacker like Dan Kaminsky wouldn't have spent 4 months just trying to prove the protocol is immune to double-spending and robust against 51% attacks. There had got to be more things that he was trying.
Exactly what kind of hacks will a hacker try to achieve against bitcoin?

user13751: There could also be hacks targeting the bitcoin software implementation. If a vulerability is applicable to software running on majority (>50% hashrate) of the nodes then it is a real threat.
For example lets say someone can craft a mal-formed transaction that somehow can trick >50% nodes to accept it (for example induce a buffer overflow and somehow allow attacker to gain remote access to the node system itself and make modifications) then bad things will happen.

1475: <p>Dan Kaminsky said that he spent 4 months <a href="http://www.businessinsider.com/dan-kaminsky-highlights-flaws-bitcoin-2013-4?IR=T&amp;" rel="nofollow noreferrer">trying to hack "bitcoin"</a> but failed.</p>

<p>Besides trying to find vulnerabilities in <a href="https://bitcoin.stackexchange.com/q/421/1475">double-spending</a> and <a href="https://bitcoin.stackexchange.com/q/1061/1475">51% attack</a>, what other hacks would a hacker try to achieve?</p>

<p>Surely an established hacker like Dan Kaminsky wouldn't have spent 4 months just trying to prove the protocol is immune to double-spending and robust against 51% attacks. There had got to be more things that he was trying.</p>

<p>Exactly what kind of hacks will a hacker try to achieve against bitcoin?</p>
 13751: <p>There could also be hacks targeting the bitcoin software implementation. If a vulerability is applicable to software running on majority (>50% hashrate) of the nodes then it is a real threat.</p>

<p>For example lets say someone can craft a mal-formed transaction that somehow can trick >50% nodes to accept it (for example induce a buffer overflow and somehow allow attacker to gain remote access to the node system itself and make modifications) then bad things will happen.</p>
