blockchain-security

Name: blockchain-security
Author: transilienceai

423stars74forks

How to install blockchain-security?

transilienceai/communitytools/blockchain-security

$npx -y skills add transilienceai/communitytools --skill blockchain-security

Installs into the current project.

Summary

Smart contract security testing and blockchain CTF exploitation. Covers Solidity vulnerability analysis, EVM storage manipulation, delegatecall attacks, CREATE/CREATE2 address prediction, and common DeFi exploit patterns. Use when analyzing Solidity contracts, solving blockchain

Files · 1

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SKILL.md

1	# Blockchain Security
2
3	## Quick Start
4	1. Download and decompile contracts (source or bytecode)
5	2. Map storage layout and identify privileged operations
6	3. Check for delegatecall, CREATE address prediction, reentrancy, access control
7	4. Deploy exploit contracts via web3.py or cast/forge
8	5. Verify win condition (isSolved/flag endpoint)
9
10	## Blockchain CTF Challenge Pattern
11	```bash
12	# Get connection info
13	curl http://$HOST:$PORT/connection_info # -> PrivateKey, Address, TargetAddress, setupAddress
14	# RPC endpoint
15	RPC_URL="http://$HOST:$PORT/rpc"
16	# Win condition: Setup.isSolved() must return true
17	```
18
19	## Key Attack Vectors
20
21	### 1. Delegatecall Storage Manipulation
22	When contract A does `delegatecall` to contract B, B's code runs with A's storage.
23	- Deploy exploit contract that mirrors A's storage layout
24	- Exploit contract writes to A's storage slots via delegatecall
25	- Critical: Storage layout must match exactly (same slot ordering)
26	- See [reference/delegatecall-attacks.md](reference/delegatecall-attacks.md)
27
28	### 2. CREATE Address Prediction (Nonce Manipulation)
29	Contract addresses from CREATE are deterministic: `keccak256(rlp([sender, nonce]))[12:]`
30	- Brute-force nonce to find which nonce produces target address
31	- Send dummy transactions (self-transfers) to increment nonce
32	- Deploy exploit contract at the exact nonce that hits target address
33	- See [reference/create-address-prediction.md](reference/create-address-prediction.md)
34
35	### 3. Storage Layout & Slot Computation
36	- Mappings: `keccak256(h(key) \|\| uint256(slot_number))`
37	- Value types: `h(k) = abi.encode(k)` (left-padded to 32 bytes)
38	- String/bytes: `h(k) = keccak256(k)`
39	- Read private variables via `eth_getStorageAt`
40	- See [reference/storage-layout.md](reference/storage-layout.md)
41
42	### 4. Empty Array / Zero-Length Input Bypass
43	When a function loops over a user-supplied array to validate items (signatures, approvals, votes), passing an empty array skips the loop entirely. If there's no minimum-length check, validation is bypassed.
44	- Check: `for (uint i = 0; i < arr.length; i++)` with no `require(arr.length >= N)`
45	- Exploit: Call the function with `[]` to skip all validation
46
47	### 5. ECDSA Signature Malleability
48	Raw `ecrecover` accepts both `(v, r, s)` and `(v', r, N-s)` (where N = secp256k1 order, v flipped 27↔28). If a contract deduplicates signatures by hash of raw bytes, the malleable form has a different hash but recovers to the same signer.
49	- Check: `ecrecover` used without `s <= N/2` enforcement (OpenZeppelin's ECDSA.sol enforces this)
50	- Exploit: Take a known valid signature, compute `new_s = N - s`, flip `v`, submit as "new" signature
51
52	### 6. Common Vulnerability Classes
53	\| Vulnerability \| Check \|
54	\|---\|---\|
55	\| Reentrancy \| External calls before state updates \|
56	\| Access control \| Missing onlyOwner / msg.sender checks \|
57	\| Integer overflow \| Solidity < 0.8.0 without SafeMath \|
58	\| Delegatecall injection \| User-controlled delegatecall target \|
59	\| tx.origin auth \| `tx.origin` instead of `msg.sender` \|
60	\| Selfdestruct \| Force-send ETH, reset contract nonce \|
61	\| Weak randomness \| blockhash/timestamp as entropy source \|
62	\| Empty array bypass \| Loop validation with no min-length check \|
63	\| Signature malleability \| Raw ecrecover without s-normalization \|
64
65	## Tools
66	```python
67	# web3.py essentials
68	from web3 import Web3
69	w3 = Web3(Web3.HTTPProvider(RPC_URL))
70	acct = w3.eth.account.from_key(PRIVATE_KEY)
71
72	# Read private storage
73	w3.eth.get_storage_at(contract_addr, slot)
74
75	# Deploy contract
76	from solcx import compile_source, install_solc
77	install_solc("0.8.13")
78	compiled = compile_source(source, output_values=["abi", "bin"], solc_version="0.8.13")
79
80	# Send raw bytecode deployment
81	tx = {'data': bytecode, 'gas': 3000000, 'gasPrice': w3.eth.gas_price, 'nonce': nonce, 'chainId': chain_id}
82	signed = acct.sign_transaction(tx)
83	w3.eth.send_raw_transaction(signed.raw_transaction)
84	```
85
86	## Reference
87	- [Delegatecall Attacks](reference/delegatecall-attacks.md)
88	- [CREATE Address Prediction](reference/create-address-prediction.md)
89	- [Storage Layout](reference/storage-layout.md)
90
91	## Critical Rules
92	- Always read storage before attacking (private vars are readable on-chain)
93	- Mirror exact storage layout when exploiting delegatecall
94	- For CREATE nonce brute-force, check nonces 0-100000+ systematically
95	- CTF instances are often ephemeral -- script the full attack for speed

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6 picks

Type

blockchain-security

423stars74forks

View on GitHub

How to install blockchain-security?

transilienceai/communitytools/blockchain-security

$npx -y skills add transilienceai/communitytools --skill blockchain-security

Installs into the current project.

Summary

Files · 1

View on GitHub

SKILL.md

1	# Blockchain Security
2
3	## Quick Start
4	1. Download and decompile contracts (source or bytecode)
5	2. Map storage layout and identify privileged operations
6	3. Check for delegatecall, CREATE address prediction, reentrancy, access control
7	4. Deploy exploit contracts via web3.py or cast/forge
8	5. Verify win condition (isSolved/flag endpoint)
9
10	## Blockchain CTF Challenge Pattern
11	```bash
12	# Get connection info
13	curl http://$HOST:$PORT/connection_info # -> PrivateKey, Address, TargetAddress, setupAddress
14	# RPC endpoint
15	RPC_URL="http://$HOST:$PORT/rpc"
16	# Win condition: Setup.isSolved() must return true
17	```
18
19	## Key Attack Vectors
20
21	### 1. Delegatecall Storage Manipulation
22	When contract A does `delegatecall` to contract B, B's code runs with A's storage.
23	- Deploy exploit contract that mirrors A's storage layout
24	- Exploit contract writes to A's storage slots via delegatecall
25	- Critical: Storage layout must match exactly (same slot ordering)
26	- See [reference/delegatecall-attacks.md](reference/delegatecall-attacks.md)
27
28	### 2. CREATE Address Prediction (Nonce Manipulation)
29	Contract addresses from CREATE are deterministic: `keccak256(rlp([sender, nonce]))[12:]`
30	- Brute-force nonce to find which nonce produces target address
31	- Send dummy transactions (self-transfers) to increment nonce
32	- Deploy exploit contract at the exact nonce that hits target address
33	- See [reference/create-address-prediction.md](reference/create-address-prediction.md)
34
35	### 3. Storage Layout & Slot Computation
36	- Mappings: `keccak256(h(key) \|\| uint256(slot_number))`
37	- Value types: `h(k) = abi.encode(k)` (left-padded to 32 bytes)
38	- String/bytes: `h(k) = keccak256(k)`
39	- Read private variables via `eth_getStorageAt`
40	- See [reference/storage-layout.md](reference/storage-layout.md)
41
42	### 4. Empty Array / Zero-Length Input Bypass
43	When a function loops over a user-supplied array to validate items (signatures, approvals, votes), passing an empty array skips the loop entirely. If there's no minimum-length check, validation is bypassed.
44	- Check: `for (uint i = 0; i < arr.length; i++)` with no `require(arr.length >= N)`
45	- Exploit: Call the function with `[]` to skip all validation
46
47	### 5. ECDSA Signature Malleability
48	Raw `ecrecover` accepts both `(v, r, s)` and `(v', r, N-s)` (where N = secp256k1 order, v flipped 27↔28). If a contract deduplicates signatures by hash of raw bytes, the malleable form has a different hash but recovers to the same signer.
49	- Check: `ecrecover` used without `s <= N/2` enforcement (OpenZeppelin's ECDSA.sol enforces this)
50	- Exploit: Take a known valid signature, compute `new_s = N - s`, flip `v`, submit as "new" signature
51
52	### 6. Common Vulnerability Classes
53	\| Vulnerability \| Check \|
54	\|---\|---\|
55	\| Reentrancy \| External calls before state updates \|
56	\| Access control \| Missing onlyOwner / msg.sender checks \|
57	\| Integer overflow \| Solidity < 0.8.0 without SafeMath \|
58	\| Delegatecall injection \| User-controlled delegatecall target \|
59	\| tx.origin auth \| `tx.origin` instead of `msg.sender` \|
60	\| Selfdestruct \| Force-send ETH, reset contract nonce \|
61	\| Weak randomness \| blockhash/timestamp as entropy source \|
62	\| Empty array bypass \| Loop validation with no min-length check \|
63	\| Signature malleability \| Raw ecrecover without s-normalization \|
64
65	## Tools
66	```python
67	# web3.py essentials
68	from web3 import Web3
69	w3 = Web3(Web3.HTTPProvider(RPC_URL))
70	acct = w3.eth.account.from_key(PRIVATE_KEY)
71
72	# Read private storage
73	w3.eth.get_storage_at(contract_addr, slot)
74
75	# Deploy contract
76	from solcx import compile_source, install_solc
77	install_solc("0.8.13")
78	compiled = compile_source(source, output_values=["abi", "bin"], solc_version="0.8.13")
79
80	# Send raw bytecode deployment
81	tx = {'data': bytecode, 'gas': 3000000, 'gasPrice': w3.eth.gas_price, 'nonce': nonce, 'chainId': chain_id}
82	signed = acct.sign_transaction(tx)
83	w3.eth.send_raw_transaction(signed.raw_transaction)
84	```
85
86	## Reference
87	- [Delegatecall Attacks](reference/delegatecall-attacks.md)
88	- [CREATE Address Prediction](reference/create-address-prediction.md)
89	- [Storage Layout](reference/storage-layout.md)
90
91	## Critical Rules
92	- Always read storage before attacking (private vars are readable on-chain)
93	- Mirror exact storage layout when exploiting delegatecall
94	- For CREATE nonce brute-force, check nonces 0-100000+ systematically
95	- CTF instances are often ephemeral -- script the full attack for speed

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6 picks

Type