Reverse Engineering
1. Run a Foundry Script with Broadcast
forge script script/Counter.s.sol:CounterScript \
--rpc-url http://127.0.0.1:8545 \
--private-key 0x8fab1c7c3e750b4c261f4aa6d318a66e0a938ec87cb2a94de6e62d7aa2deef8d \
--broadcast
2. Get Deployed Bytecode
cat out/HelloWorld.sol/HelloWorld.json | jq -r '.deployedBytecode.object'
3. Disassemble to Opcodes
cast disassemble <your_bytecode>
4. Lookup Function Selector
-
Website: https://www.4byte.directory/signatures/?bytes4_signature=d09de08a
-
Or using Foundry:
cast 4byte 0xd09de08a
5. Explore EVM Opcodes
- Website: https://www.evm.codes/playground
6. Cast Call to Contract Function
cast call 0x06a4F27D78F5c60AE98CE5Cd666CCe8c1B105feA d09de08a \
--rpc-url http://127.0.0.1:8545
1. Running a Foundry Script with Broadcast
root@lenova:/mnt/c/users/pedda/onedrive/desktop/foundry-test/ctf# cast code 0xd88F9d3aE66CDf815aAFfEA73db14ffC69843429 --rpc-url http://127.0.0.1:8545
Warning: This is a nightly build of Foundry. It is recommended to use the latest stable version. Visit https://book.getfoundry.sh/announcements for more information.
To mute this warning set `FOUNDRY_DISABLE_NIGHTLY_WARNING` in your environment.
0x608060405234801561000f575f80fd5b506004361061004a575f3560e01c80633fb5c1cb1461004e5780638381f58a1461006a578063cfae321714610088578063d09de08a146100a6575b5f80fd5b6100686004803603810190610063919061014a565b6100b0565b005b6100726100b9565b60405161007f9190610184565b60405180910390f35b6100906100be565b60405161009d919061020d565b60405180910390f35b6100ae6100fb565b005b805f8190555050565b5f5481565b60606040518060400160405280600f81526020017f48656c6c6f2c20466f756e647279210000000000000000000000000000000000815250905090565b5f8081548092919061010c9061025a565b9190505550565b5f80fd5b5f819050919050565b61012981610117565b8114610133575f80fd5b50565b5f8135905061014481610120565b92915050565b5f6020828403121561015f5761015e610113565b5b5f61016c84828501610136565b91505092915050565b61017e81610117565b82525050565b5f6020820190506101975f830184610175565b92915050565b5f81519050919050565b5f82825260208201905092915050565b8281835e5f83830152505050565b5f601f19601f8301169050919050565b5f6101df8261019d565b6101e981856101a7565b93506101f98185602086016101b7565b610202816101c5565b840191505092915050565b5f6020820190508181035f83015261022581846101d5565b905092915050565b7f4e487b71000000000000000000000000000000000000000000000000000000005f52601160045260245ffd5b5f61026482610117565b91507fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff82036102965761029561022d565b5b60018201905091905056fea26469706673582212201b3d0841a77246d2d2d4ed649f8652f86f4069ba9b22c247d9cd7a531cd59b8864736f6c634300081a0033
root@lenova:/mnt/c/users/pedda/onedrive/desktop/foundry-test/ctf# cast disassemble 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
[00] PUSH1 80
[02] PUSH1 40
[04] MSTORE
[05] CALLVALUE
[06] DUP1
[07] ISZERO
[08] PUSH1 0f
[0a] JUMPI
[0b] PUSH1 00
[0d] DUP1
[0e] REVERT
[0f] JUMPDEST
[10] POP
[11] PUSH2 030a
[14] DUP1
[15] PUSH2 001f
[18] PUSH1 00
[1a] CODECOPY
[1b] PUSH1 00
[1d] RETURN
[1e] INVALID
[1f] PUSH1 80
[21] PUSH1 40
[23] MSTORE
[24] CALLVALUE
[25] DUP1
[26] ISZERO
[27] PUSH2 0010
[2a] JUMPI
[2b] PUSH1 00
[2d] DUP1
[2e] REVERT
[2f] JUMPDEST
[30] POP
[31] PUSH1 04
[33] CALLDATASIZE
[34] LT
[35] PUSH2 004c
[38] JUMPI
[39] PUSH1 00
[3b] CALLDATALOAD
[3c] PUSH1 e0
[3e] SHR
[3f] DUP1
[40] PUSH4 3fb5c1cb
[45] EQ
[46] PUSH2 0051
[49] JUMPI
[4a] DUP1
[4b] PUSH4 8381f58a
[50] EQ
[51] PUSH2 006d
[54] JUMPI
[55] DUP1
[56] PUSH4 cfae3217
[5b] EQ
[5c] PUSH2 008b
[5f] JUMPI
[60] DUP1
[61] PUSH4 d09de08a
[66] EQ
[67] PUSH2 00a9
[6a] JUMPI
[6b] JUMPDEST
[6c] PUSH1 00
[6e] DUP1
[6f] REVERT
[70] JUMPDEST
[71] PUSH2 006b
[74] PUSH1 04
[76] DUP1
[77] CALLDATASIZE
[78] SUB
[79] DUP2
[7a] ADD
.....
...
...
....
...
...
..
[311] INVALID
[312] INVALID
[313] INVALID
[314] GT
[315] PUSH19 dcbf77d7b3325a4d64736f6c634300081a0033
# Foundry `cast 4byte` Usage Example and Interaction Notes
```bash
root@lenova:/mnt/c/users/pedda/onedrive/desktop/foundry-test/ctf# cast 4byte 0xd09de08a
Warning: This is a nightly build of Foundry. It is recommended to use the latest stable version. Visit https://book.getfoundry.sh/announcements for more information.
To mute this warning set `FOUNDRY_DISABLE_NIGHTLY_WARNING` in your environment.
increment()
root@lenova:/mnt/c/users/pedda/onedrive/desktop/foundry-test/ctf#
Here is your table properly formatted in Markdown syntax, exactly as you requested:
| You Have | Can You Interact? | Notes |
|---|---|---|
| Function Selector only | No | Need at least an address. |
| Selector + Inputs | No | Still need address. |
| Address + Selector | Yes (via cast call) | ABI optional if calldata is correct. |
| Full ABI + Address | Yes (Easy interaction) | Best for development use. |