WEBVTT 00:00.000 --> 00:04.860 My talk on Modeling Systemic Threat Using Mainnet Fork. 00:05.020 --> 00:09.360 And so, next one, who am I? 00:10.040 --> 00:15.580 I'm Martinet Li, a Research Engineer slash Security Auditor from QuantStamp. 00:15.580 --> 00:23.640 And since last year, I reviewed a lot of projects, especially in the DeFi space, as this particular space is booming. 00:24.060 --> 00:29.980 But I was also involved in some reviews on, you know, base layer chains. 00:30.000 --> 00:36.380 Like Eth2, Prism Implementation, and AvaLabs as well. 00:36.420 --> 00:40.800 And the girl beside me, that's my daughter, just by the way. 00:40.800 --> 00:42.240 And next one. 00:42.480 --> 00:53.340 So, what this presentation is about, I kind of want to be more like a light talk and perhaps interactive, so feel free to just shoot me any questions in between. 00:53.380 --> 00:59.080 But basically, what I wanted to share today is kind of the status quo on testing. 00:59.080 --> 01:04.020 From an auditor's point of view, and mainly focusing on composability. 01:04.600 --> 01:11.560 As projects integrate with others more closely, how are people right now testing their projects? 01:11.560 --> 01:14.580 And what I believe would be beneficial. 01:15.160 --> 01:22.180 I will also introduce my personal project on trying to improve testing with two simple examples here. 01:22.960 --> 01:24.920 So, next one. 01:25.720 --> 01:30.520 So, the main challenge here is the composability. 01:30.520 --> 01:32.420 So, what is composability? 01:32.560 --> 01:41.620 It is a feature of design wherein the various components of a system can be easily connected to form any number of satisfying results. 01:41.620 --> 01:44.280 That's from MakerDAO. 01:44.280 --> 01:51.380 And although blockchain projects have always been composable, you know, like it's always open API, right? 01:51.380 --> 02:03.280 Its power was really unleashed by the DeFi space, and especially the standardization of these token interfaces like ERC-20, ERC-721. 02:04.300 --> 02:13.220 In the beginning, we see most of projects focusing just building on their own ecosystem, pretty much independent from other projects. 02:13.220 --> 02:18.500 They issue these tokens just hoping other to use, maybe to trade. 02:18.500 --> 02:31.340 You know, but then with the use of these standardized interfaces, it allows like other projects to leverage like what, well, it allows projects to leverage one another, right? 02:31.340 --> 02:32.740 Kind of like Lego. 02:32.740 --> 02:35.500 So, that's the term money Lego. 02:35.920 --> 02:41.920 And easily connecting them together to create like so many different kinds of functionalities. 02:41.920 --> 02:48.480 Of course, exchanges are the first one, you know, just aggregates just using the interface and then sell them. 02:48.500 --> 02:53.940 They're just using the token, not really the internal functionality, right? 02:54.380 --> 03:04.880 Another piece which is important to this composability, which not necessarily fits into like this money Lego thing is the Oracle part. 03:04.880 --> 03:12.240 Oracle feeds us like maybe real world data and then allows us to use them on chain. 03:12.240 --> 03:17.660 So, it is also like an important piece in this composability, I would say. 03:18.220 --> 03:19.860 So, next one. 03:21.800 --> 03:25.580 So, composability is certainly a blessing. 03:25.580 --> 03:32.860 So, we see that there are so many interesting projects in the past few years that emerges from here, right? 03:32.860 --> 03:40.400 Pulled together as one example, it builds like no loss lottery on top of the compound protocol, right? 03:40.520 --> 03:45.200 So, as time goes by, like projects tend to grow more complex. 03:45.200 --> 03:50.280 One of the prime example recently would be the Yearn protocol, right? 03:50.280 --> 04:00.980 That helps user yield farming by putting together like Curve, AVI, Compound, MStable, and a lot of other protocols, right? 04:00.980 --> 04:09.980 I would say it's one of the amazing projects that full of creativity and demonstrate what can be done with this composability. 04:11.120 --> 04:12.800 Now, next. 04:13.600 --> 04:18.860 However, this composability is also a curse, right? 04:18.860 --> 04:26.660 So, we have already witnessed several attacks and one systematic failure that affected the whole DeFi community. 04:26.660 --> 04:38.740 And I'll just like bring up a simple example here, which is the first BZX attack, which involves a DYDX, Compound, BZX, Kyber, and Uniswap, right? 04:38.740 --> 04:53.740 It uses the DYDX, a flagship ability, and then borrow WBTC from Compound, uses BZX as a platform to short ETH in favor of WBTC. 04:53.740 --> 05:05.480 And in turn, because internally like Kyber and Uniswap was used in the BZX, it drove up the price of WBTC and Uniswap. 05:05.480 --> 05:11.580 And then the hacker was able to just dump the WBTC and profit from there. 05:11.580 --> 05:19.120 So, you see like this complexity is also opens a lot of like, you know, different kinds of attack. 05:19.440 --> 05:20.980 That's for one. 05:20.980 --> 05:22.660 And next. 05:24.760 --> 05:28.980 And we also see like in the black Thursday, right? 05:29.260 --> 05:35.320 Not sure if the graph is visible, but we probably all know, they grew up for 30%. 05:36.740 --> 05:44.520 At the same time, so MakerDAO price did not update for a while. 05:44.520 --> 05:46.420 So they do have like Oracle. 05:46.420 --> 05:51.820 But during that time, the gas price was extremely high. 05:51.880 --> 05:57.920 And thus the price was not able to update in real time. 05:57.920 --> 06:02.620 And when it updated, it triggered like a massive liquidation. 06:03.210 --> 06:10.420 In turn, this is one of the reasons why like, there are so many collateral were auctioned off for zero. 06:10.980 --> 06:17.440 So, part of this is because of the Oracle issue here. 06:18.140 --> 06:19.320 So, next. 06:21.160 --> 06:27.040 So, I would say composability is almost like a nightmare for developers. 06:27.040 --> 06:37.900 Repeatedly see this issue, like causes a lot of troubles for developers, especially when it comes to testing the project, right? 06:37.900 --> 06:44.260 Like, how should the developer ensure the project that they interface with are working as expected? 06:44.580 --> 06:48.880 And then how, like, this is already hard, right? 06:48.880 --> 06:57.300 And so, I don't really see anyone like testing extreme scenarios, like the ones that we would mention above. 06:58.220 --> 07:00.660 So, let's go on to the next. 07:02.280 --> 07:06.980 So, the status quo on testing, kind of doing a review. 07:07.600 --> 07:18.160 What we see as auditors, typically, you know, if they have tests, they have unit tests, they have functional tests, like for internal protocol. 07:18.780 --> 07:28.180 But when it comes to testing the integration points with other projects, what we see, you know, some variety there. 07:28.300 --> 07:37.920 For the simple ones, if the external project is really simple, then you can deploy the external projects locally, you know, just in the ganache. 07:37.920 --> 07:40.300 This is possible when it's small, right? 07:40.300 --> 07:46.020 But it's impossible if the external project is complicated. 07:46.020 --> 07:50.880 Just imagine, like, you're deploying the whole MakerDAO system. 07:50.880 --> 07:52.860 Well, that's going to be a nightmare. 07:53.820 --> 07:54.740 Next. 07:55.280 --> 08:02.140 And so, there's the second option, which is mocking the external protocol, right? 08:02.140 --> 08:08.160 A developer has to understand what the external contract would do and mock the behavior accordingly. 08:09.200 --> 08:20.940 Oftentimes, developers will simplify these logic to, you know, to not really implement everything in the protocol, but just the behavior. 08:20.940 --> 08:27.300 And so, there are possible discrepancies between the mocked contract and the real behavior. 08:27.300 --> 08:30.800 And that actually presents a potential risk. 08:31.340 --> 08:36.640 Now, next on, we have testing on testnet, right? 08:36.640 --> 08:41.120 If you're interfacing with just one project, it kind of works. 08:41.120 --> 08:45.980 Although, it's still tedious to get all the test tokens, testnet tokens, and, like, Ether. 08:45.980 --> 08:47.900 You need the faucet for that. 08:48.020 --> 09:00.440 But if you're building a project that interfaces with different projects, then you can see on the right-hand side, like, this is how, you know, projects on the testnet would look like. 09:00.440 --> 09:03.620 Like, MakerDAO, they probably have their own testnet. 09:03.620 --> 09:09.900 But for sure, I know Aave and Compound, they use, like, different dymocks on the testnet. 09:09.900 --> 09:26.920 And so, if you're testing, if you are writing a project that interfaces with both Aave and Compound and want to use dye in between, this is simply different, you know, from the structure in mainnet. 09:27.140 --> 09:29.000 Now, next. 09:29.960 --> 09:35.060 Ah, well, here we have testing on mainnet. 09:35.060 --> 09:38.060 And needless to say, this is super costly. 09:38.420 --> 09:45.100 Typically, it only allows functional and high-level manual testing, you know. 09:45.100 --> 09:52.140 And so, among all these, I would say the most common ones are mocking. 09:52.940 --> 09:58.120 But testing on testnet do exist, but typically done, like, not very extensively. 09:59.000 --> 10:08.700 Because developers, like, oftentimes find, you know, fetching those resources very, very troublesome, right? 10:08.700 --> 10:15.480 And so, I have personally seen projects that did both the mock and testing on testnet. 10:15.480 --> 10:22.320 So that's, you know, they are, you can see that they're trying their best, but still missed to test the profit sharing. 10:22.320 --> 10:30.300 Because that requires some understanding of the underlying protocol and how they would behave. 10:30.300 --> 10:32.280 So they missed that in the mock. 10:32.860 --> 10:44.380 And then on the testnet, because it was kind of like one-shot testing, it doesn't really wait for the time and wait for the profit to accrue. 10:44.380 --> 10:47.300 So, like, they missed the profit sharing part. 10:47.400 --> 10:50.420 And we were able to locate that issue, luckily. 10:51.080 --> 11:06.660 After that, I sort of see this as this lack of testing facility that helps, you know, testing, like, composability thing is a huge security issue for the whole ecosystem. 11:07.940 --> 11:08.920 Next. 11:11.120 --> 11:19.260 And so, with the standard tool, actually, I do, there are one option that I would say it's quite nice. 11:20.420 --> 11:24.340 I do recommend, like, testing under this mainnet fork. 11:24.340 --> 11:35.240 And Ganache provides this fork option, which, surprisingly, I haven't seen any project uses this to test external library. 11:35.700 --> 11:41.120 And that's probably because of my side note right there. 11:41.420 --> 11:44.720 The fork does have some bug. 11:45.280 --> 11:58.800 You know, when you use Uniswap, you probably, you'll face some weird re-entrancy error, like reverts, but you never did a re-entrancy there. 11:59.040 --> 12:03.140 So, but there is a pull request, but I don't think a lot of people know that. 12:03.140 --> 12:06.740 I think that's probably one of the reasons that this is not used. 12:06.740 --> 12:13.920 But if this is used and fixed, then I see this is actually pretty nice. 12:14.520 --> 12:20.360 Projects interconnect with each other the same way as mainnet, because it's the mainnet fork. 12:20.360 --> 12:24.020 There's, of course, no cost, because it's a local Ganache. 12:24.140 --> 12:29.820 And then huge amount of ethers when starting up the local blockchain, as always. 12:30.500 --> 12:35.160 And, you know, Ganache also allows you to sign transaction as other accounts. 12:35.160 --> 12:39.120 So you can be the whale, you know, anytime. 12:39.120 --> 12:41.120 So this is already pretty nice. 12:41.830 --> 12:42.610 Next. 12:43.480 --> 12:52.220 So with this, we can already start to model a systemic threat, which is the whale, right? 12:52.220 --> 12:59.620 For example, to be a die whale here, well, you can use an unlock account. 13:00.060 --> 13:13.560 You find some die whale on the mainnet and, you know, just write his address down, unlock his address on your local Ganache and use that to test. 13:13.600 --> 13:14.800 So that's good. 13:14.800 --> 13:23.780 The downside is that, well, if the whale just transfers his die to other places, then, you know, this test doesn't work anymore. 13:23.780 --> 13:26.280 You need to find another die whale. 13:26.660 --> 13:32.180 So, you know, not really reliable as test, I would say. 13:33.500 --> 13:39.380 The other two paths that you can do is that you can, of course, mint die on MakerDAO. 13:39.380 --> 13:46.360 However, that requires you to, you know, you already have that huge amount of ethers, so you can definitely do that, right? 13:46.360 --> 13:54.020 But you have to know how to open vault, lock up collateral and use that to mint die. 13:54.040 --> 13:59.120 But in the end, what you really want is just increasing your balance in the die. 13:59.120 --> 14:02.700 You know, it's pretty tedious and going through all that. 14:02.700 --> 14:04.860 And same for buying die on DEX. 14:04.860 --> 14:11.240 If you want to do that, you need to know Uniswap's interface, perhaps, and how to interact with them. 14:11.520 --> 14:16.360 So it's not as convenient. 14:17.000 --> 14:18.160 So, next. 14:20.720 --> 14:24.800 Yeah, and still, like, some risk remains very hard to model. 14:25.470 --> 14:33.780 Like, if modeling a risk involves changing the price feed on MakerDAO or Uniswap v2, that may be a problem. 14:33.940 --> 14:53.520 And then, let's say, if you want to model what would happen on your platform or your smart contract when you experience an oracle attack, like, for example, you're using Uniswap and you're also using Chainlink as your oracle. 14:53.520 --> 15:01.120 What would happen if there is a mismatch on my protocol, right? 15:01.120 --> 15:02.620 Can I model that? 15:03.180 --> 15:07.760 And then, you know, seeing the BZX attack, that's pretty sophisticated. 15:08.180 --> 15:12.600 It might be very hard to come up with that sort of scenarios. 15:12.600 --> 15:24.040 And so, one thing that you might want to do is just assume that there could be a mismatch in the oracle price, then what would happen, right? 15:24.040 --> 15:25.420 That's much easier. 15:25.420 --> 15:33.060 But in this mainnet fork, you cannot do that because you still have to follow all the blockchain rules, right? 15:33.060 --> 15:42.580 And in general, if modeling requires, like, changing a variable that is not directly settable by an externally owned account, this is challenging. 15:43.480 --> 15:53.860 So, the question, next one, is what if we could ignore code as law, you know, on the local blockchain? 15:53.860 --> 16:00.380 And what if, like, can we change the storage directly without any permission? 16:00.820 --> 16:02.180 Next one. 16:03.500 --> 16:17.580 So, I kind of went on this direction and digged into the ganache because since this is the testing environment that most of the people are using, I decided to dig into this one and see if this can be accomplished. 16:17.680 --> 16:23.820 And so, ganache itself, it kind of looks like this, you know, like the related part. 16:23.820 --> 16:30.540 It has WS server, HTTP server, and it connects to this get API module that it has internally. 16:30.540 --> 16:40.980 This get API module controls the state manager, and it's supported by a VM, which is the Ethereum JS VM. 16:41.600 --> 16:44.980 So, next. 16:47.120 --> 17:05.440 And so, within this ganache, this state manager, you know, within this VM, then I found that in the VM state manager, there's actually a free function that is very useful for us, which is the put account, put contract code, put contract storage. 17:05.440 --> 17:15.040 By using these, essentially, you can directly modify the storage and the state of the local ganache. 17:15.140 --> 17:23.820 So, what typically was done is that you still go through ganache and send transaction to ganache. 17:23.820 --> 17:34.620 So, what I tried to do was to open up a backdoor, if you may, and say that, hey, I don't want to verify my transaction. 17:34.620 --> 17:38.620 I just directly want to modify my storage right there. 17:38.880 --> 17:44.100 So, that's the root of my project. 17:44.100 --> 17:46.160 And so, next one. 17:47.640 --> 17:53.240 So, after some development, like, this is my project, which I call Godmode for Test. 17:53.240 --> 17:55.920 It basically consists of three parts. 17:56.220 --> 18:00.920 The project itself is still in, like, very early stage and still needs a lot of work. 18:00.920 --> 18:10.560 It already works, and I personally use it for development, especially when it's come to DeFi projects. 18:10.560 --> 18:14.500 So, what I built consists of three pieces. 18:14.500 --> 18:18.520 The first one is this ganache core. 18:18.520 --> 18:27.900 So, this modified ganache core allows us to ignore the blockchain log and just directly modify the storage, as previously stated. 18:27.900 --> 18:37.100 And then, on top of that, I created a wrapper JavaScript library that you can integrate into the Truffle framework. 18:37.120 --> 18:46.900 So, you know, all the familiar tools that we use and leverage the Solidity contract as sort of an API. 18:46.900 --> 18:52.260 I think it's easier to understand how to modify the storage of the blockchain. 18:52.820 --> 18:55.680 And there's some set of precompiled contracts. 18:56.560 --> 19:00.800 So, what the precompiled contracts would do... 19:01.260 --> 19:01.920 next, please... 19:03.500 --> 19:10.740 is, you know, I want to provide some easy-to-set-up scenarios for the developers. 19:10.740 --> 19:28.580 For example, to mint Dai, you don't have to think about finding that whale and, you know, worry about the whale will transfer it away and the test won't work anymore, or worry about all the vault, you know, all the original mint Dai process. 19:28.580 --> 19:40.140 Now, what you need to do is just call this function call and then it will give Bob, you know, 10,000 Dai, which is great. 19:40.740 --> 19:41.900 Next. 19:44.060 --> 19:46.820 And in a more general sense... 19:47.580 --> 19:54.020 So, this is a general API that I provide that you can basically craft... 19:55.960 --> 20:00.720 use this to modify, like, arbitrary contract storage. 20:00.720 --> 20:06.920 And so, it might not be very clear just by seeing this. 20:06.920 --> 20:10.100 And so, I'll demonstrate a few examples. 20:10.960 --> 20:15.660 I'm happy that I have had the backup of, like, kind of all the screenshots. 20:16.380 --> 20:18.320 And so, yeah, we'll... 20:18.320 --> 20:19.540 I kind of... 20:19.540 --> 20:24.100 I will kind of walk you through, like, all the screenshots on doing these things. 20:24.660 --> 20:25.960 So, yeah. 20:25.960 --> 20:27.980 So, next one. 20:28.140 --> 20:42.780 So, we'll go through, like, the first example, which is using that general API and use it to mint Dai, you know, like, the one that I already had in the library. 20:42.780 --> 20:45.640 But right now, I just wanted to show you how this could be done. 20:45.660 --> 20:53.360 And so, the first step would be you go and find Dai's source code and mainnet address. 20:53.360 --> 20:56.620 And, of course, both are available on Etherscan. 20:56.620 --> 20:59.320 So, you go there, copy it down. 20:59.320 --> 21:05.100 I'm assuming that we're using, like, Truffle project framework here. 21:05.100 --> 21:10.140 So, we just store the Dai source code under the contracts folder. 21:10.780 --> 21:11.900 Next one. 21:15.000 --> 21:22.360 And so, the following step is we clone that Dai contract, you know, rename it. 21:22.360 --> 21:26.960 So, now we would have, like, let's say two contracts. 21:26.960 --> 21:27.940 One is Dai. 21:27.940 --> 21:31.260 Let's say the other one is called gmDai. 21:32.500 --> 21:36.080 And we modify the mint function. 21:36.080 --> 21:39.140 So, how we modify it, it's really simple. 21:39.140 --> 21:45.980 The reason that we cannot mint Dai is it was authorized. 21:45.980 --> 21:47.880 Like , it is controlled. 21:48.600 --> 21:55.420 There's a requirement statement that prevents us from going in, which is this modifier auth, right? 21:55.420 --> 21:59.540 So, what we can do is just to remove that auth. 21:59.540 --> 22:05.380 And that allows anyone to call this mint. 22:05.380 --> 22:10.040 So, you know, that's essentially how it's done. 22:10.180 --> 22:10.940 Next. 22:14.080 --> 22:20.460 And so, in the normal test, and this is how we would write it. 22:20.740 --> 22:30.540 So, we have, we would require both artifacts, include both artifacts into the test, which is the Dai and gmDai. 22:30.540 --> 22:37.500 So, you recognize gmDai is the one that we just modified and removed the modifier, right? 22:38.160 --> 22:51.600 And, you know, and like all other stuff are pretty much just set up, basic setup, like, you know, talking to the Godmode Ganache and all that. 22:51.600 --> 23:01.740 But the real essential part is the part that I, you know, had with the red square or rectangle, whatever, that's the executeAs. 23:01.740 --> 23:07.580 So, what you do here is actually you're executing the Dai contract. 23:07.580 --> 23:11.960 So, you see this Dai contract is just like two lines above. 23:11.960 --> 23:15.860 It's, it was like a way to Dai at this address. 23:15.860 --> 23:20.880 And that's the address of the main net Dai address, right? 23:20.880 --> 23:31.440 And so, I execute this Dai contract as if it is the modified contract. 23:31.740 --> 23:38.800 So, I'm actually just executing, you can think of it that this way. 23:38.800 --> 23:43.560 So, I am modifying the storage of Dai contract. 23:43.560 --> 23:51.840 But according to the rules set by this gmDai artifact or contract. 23:51.840 --> 23:58.760 And so, here, essentially, I'm just calling mint from the gmDai contract. 23:58.760 --> 24:02.600 Then I say, give Alice this amount of Dai. 24:02.740 --> 24:05.140 And the next line is assertion. 24:05.280 --> 24:10.160 And so, this is, yeah, this is basically how it works. 24:11.420 --> 24:12.760 Next one. 24:15.360 --> 24:19.400 Now, so, that's the, that's just minting Dai. 24:19.400 --> 24:25.060 And so, as a second example, I'll show you how to modify to make a DAO price feed. 24:25.060 --> 24:36.260 Now, this is an essential step for modeling this systemic threat, like, you know, oracle attacks and all of that. 24:36.260 --> 24:47.460 Because what you want to do is to have, like, maybe two oracles report different values, right? 24:47.460 --> 24:52.100 So, you want to read and perhaps change to make one of the oracles price feed. 24:52.100 --> 24:53.980 Here, I chose my DAO. 24:53.980 --> 24:59.360 And, of course, you just Google and find out where the maker DAO is getting their price. 25:00.300 --> 25:05.160 And so, this is the address that I found on their page. 25:05.200 --> 25:10.540 And then you just go to that ether scan the same way we did as Dai. 25:10.540 --> 25:12.540 And then copy the source code. 25:13.400 --> 25:14.680 Next one. 25:17.590 --> 25:22.270 Yeah, and, you know, this is still a little bit technical. 25:22.270 --> 25:25.970 You have to understand kind of how it works. 25:25.970 --> 25:29.070 But luckily, most of the oracles are pretty simple. 25:29.070 --> 25:31.590 They're basically reporting what they have. 25:31.590 --> 25:33.310 Maybe they have something else. 25:33.310 --> 25:38.790 Like, in this maker DAO price feed, this OSM module is their oracle. 25:38.790 --> 25:42.870 I think it's oracle security module or something like that. 25:43.210 --> 25:46.870 So, OSM module basically has an example. 25:46.870 --> 25:49.770 Hey, OSM peak is getting the current value. 25:49.770 --> 25:52.670 Or OSM read is getting the current value or fail. 25:52.670 --> 25:56.330 And so, you go and look at the source code of OSM. 25:56.330 --> 26:04.290 And you find out that, ah, it is actually returning the value from this curr.val, right? 26:04.290 --> 26:08.210 So, this is where the current value is storing. 26:08.990 --> 26:14.590 And so, what we want to do is basically just read this one. 26:14.590 --> 26:20.190 And, you know, and perhaps modify it. 26:20.190 --> 26:31.470 And so, the reason I say read is that if you later take a look at the OSM contract, you see, well, you see right here, actually. 26:31.470 --> 26:34.330 There's a modifier called tall. 26:34.330 --> 26:42.510 And that prevents any user, like, external contracts from using, from reading the value here. 26:42.510 --> 26:49.450 But if we want to just use, just inspect this value, we can actually do that. 26:50.290 --> 26:51.170 But, okay. 26:51.170 --> 26:52.450 So, next one. 26:56.560 --> 27:02.660 And so, yeah, kind of same way we did on the die to GM die. 27:02.660 --> 27:12.520 So, we modify the clone OSM module, add these two functions and event. 27:12.520 --> 27:21.100 The reason I do event is that, unfortunately, right now, it doesn't read. 27:21.440 --> 27:28.880 So , this execute as cannot just read a function. 27:28.880 --> 27:31.500 You know, like, it will always do a state change. 27:31.500 --> 27:35.960 So, if you do a view function, then it will revert on that. 27:35.960 --> 27:37.960 So, this is kind of a workaround. 27:37.960 --> 27:41.740 But nevertheless, you can still get the value this way. 27:41.740 --> 27:47.440 And then, the next one is pretty simple, which is just setting that current value. 27:47.440 --> 27:47.540 Right ? 27:47.540 --> 27:52.300 So, set curve val and curve dot val equals to the new value that we have. 27:52.860 --> 27:54.060 Next one. 27:56.620 --> 28:03.760 And so, with this, you know, we can just write test to check the behavior. 28:04.700 --> 28:19.840 Similar way as we would say that this OSM contract is the OSM at, you know, the original address that this contract were placed. 28:19.980 --> 28:26.580 And then, the next two lines, this transaction, weird transaction thing is reading from the logs. 28:26.580 --> 28:28.560 Basically, reading from the events. 28:28.560 --> 28:33.640 And then, reading the current value out of that event. 28:35.160 --> 28:39.960 So, in the middle, there's this await got node execute. 28:39.960 --> 28:41.980 So, here, again, it's the same thing. 28:41.980 --> 28:48.300 We're executing this OSM contract as our modified contract. 28:48.300 --> 28:54.160 And now, you see that this set curve val is a function that we added. 28:54.160 --> 28:57.820 It's not anywhere in the original contract. 28:57.820 --> 29:00.000 And we just added that part. 29:00.000 --> 29:06.160 But now, this modified ganache will be able to run this thing. 29:06.320 --> 29:13.080 And then, it will just set the curve that val into this new function. 29:13.080 --> 29:14.100 Oh, sorry, value. 29:14.660 --> 29:19.980 And I just printed out, print the value again to see what's there. 29:21.560 --> 29:23.000 Next one. 29:24.420 --> 29:27.860 So, now, yeah, this is kind of the result. 29:27.860 --> 29:38.080 You'll see that the original value is this, basically, 387 USD, right? 29:38.080 --> 29:43.880 And then, I just set it to some number that I just thought set there. 29:44.120 --> 29:49.340 So, now, you are able to change the make and dial price feed with this thing. 29:51.980 --> 29:54.140 Yeah, so, next one. 29:55.620 --> 30:03.440 So, some downside of this tool is that mainnet fork can be buggy for the ganache. 30:03.900 --> 30:08.800 So, the fix that I have there in the side node is not official. 30:09.740 --> 30:13.120 So, you know, sometimes, there are some bugs there. 30:13.220 --> 30:21.460 And the second one, you kind of already saw that we cannot create view function and return properly yet. 30:21.460 --> 30:22.900 So, I'm still working on that. 30:24.880 --> 30:28.300 And, of course, this is a local ganache. 30:28.300 --> 30:32.320 So, you cannot simulate how others would behave. 30:32.320 --> 30:45.620 You know, it's not like a simulation that you can see all, like, with this new values, how are people going to behave with the new incentive and stuff, right? 30:45.620 --> 30:48.380 So, you're alone in this local blockchain. 30:48.380 --> 30:51.600 That's kind of an inherent limitation here. 30:52.540 --> 30:59.440 And fourth is this arbitrary modify storage is sometimes too powerful. 30:59.440 --> 31:05.400 Because, you know, it can get you to state that are just not possible to reach. 31:06.140 --> 31:13.480 So , you have to be careful about and thinking about what kind of scenarios you want to craft. 31:13.480 --> 31:15.420 And if that is a reasonable scenario. 31:15.420 --> 31:24.960 Because before this tool, you have to think of ways to get to a state. 31:24.960 --> 31:26.910 And then you can start testing. 31:27.420 --> 31:31.420 Now, with this tool, you can get to any state directly. 31:31.420 --> 31:36.070 But whether that state makes sense or not, that's another question. 31:36.460 --> 31:41.560 So, that's another problem that we have to take care and think about. 31:41.820 --> 31:42.670 Yeah. 31:43.420 --> 31:45.400 And so, next one. 31:47.400 --> 31:56.980 Kind of a conclusion is that DeFi composability is currently both a blessing and a curse. 31:57.100 --> 32:04.980 I hope that with more testing facilities, we can turn it into a pure bliss. 32:05.680 --> 32:14.880 And as of right now, as I've said, I don't see a lot of testing on even the integration side. 32:14.880 --> 32:20.200 Let alone testing extreme scenarios to prevent systemic threats. 32:21.320 --> 32:33.200 Like, you know, I've really never seen people testing how systems would react if an Oracle attack is to happen, you know, modeling these different threats. 32:33.260 --> 32:33.780 Right? 32:33.780 --> 32:37.720 But this is mainly because there's no... 32:38.520 --> 32:42.240 Well, there are not a lot of tools that support this. 32:42.300 --> 32:43.260 Right? 32:43.260 --> 32:47.840 And so, I believe there's still a lot of space to improve in testing. 32:47.840 --> 32:51.260 Especially in terms of this composability thing. 32:51.900 --> 32:54.620 And I think we need... 32:55.500 --> 32:57.960 This presentation is almost like... 32:58.840 --> 33:04.080 I would treat it like an open invitation for everyone to kind of work on this area. 33:04.420 --> 33:19.060 I believe we need to work together to help secure all these blockchain projects and make this, you know, make the testing facilities better and make the composability not a headache anymore. 33:19.320 --> 33:20.060 Yeah. 33:20.060 --> 33:21.320 And that's it. 33:21.320 --> 33:23.480 Thank you for your time. 33:23.480 --> 33:24.640 Great presentation. 33:31.830 --> 33:32.990 All right. 33:32.990 --> 33:34.910 Any questions? 33:38.410 --> 33:40.110 Ah, I see. 33:40.110 --> 33:47.150 Are there limitations between forking mainnet from full versus archive nodes? 33:47.150 --> 33:51.530 Ah, it depends. 33:51.530 --> 33:59.350 So , I actually just used Infura, not even the full node. 33:59.350 --> 34:02.130 Oh, Infura is the full node, right? 34:02.130 --> 34:04.550 Yeah, but I've just been using Infura. 34:04.550 --> 34:12.670 And if you just care about how it's going to react at its current stage, I think that's fine. 34:13.390 --> 34:22.910 After like 30 minutes, then your test would start failing, and it will say that, hey, you know, you don't have access to archive nodes. 34:23.790 --> 34:26.180 Then that would start failing. 34:27.390 --> 34:41.590 But, you know, just for the purpose of doing unit tests on mainnet fork, especially for the integration part, I think you don't really need an archive node, to be honest. 34:42.080 --> 34:42.810 Yeah, 34:48.880 --> 34:51.040 no problem. 34:51.040 --> 34:52.220 My pleasure. 34:54.200 --> 35:03.460 Ah, yes, let me paste my GitHub repository into the chat. 35:03.860 --> 35:11.520 I have to warn everyone that this is like a very, very, you know, initial work. 35:11.520 --> 35:14.060 It works, but it's very ugly. 35:14.860 --> 35:24.240 I'm not particularly proud about the code quality, but I am pretty happy about the result that it can get me, though. 35:24.240 --> 35:26.160 So I'm happy to share. 35:35.400 --> 35:38.760 All right, any other questions? 35:38.780 --> 35:40.360 Thank you, Miko. 35:53.150 --> 35:54.650 Thank you. 35:54.650 --> 35:56.230 Thank you. 35:56.230 --> 35:59.450 Do we have other questions, like in Twitch?