chain-construct-smart-contract

Smart-contract specialization of chain-construct for exploit-developer: build multi-step attack call sequences for on-chain vulnerabilities and prove them with a passing Forge (EVM) or LiteSVM/Trident (Solana) reproduction. Follow the generic chain-construct method (objective as end-state, chain head, state-feeds ordering, prove-don't-assert); this skill adds the EVM/Solana chain primitives. Where the two conflict, the contract-level guidance here wins for smart-contract targets. All tools are native host CLIs (forge, cargo test/litesvm, trident, cargo-fuzz, anchor) — no wrapper layer.

Chain primitives — EVM

Reentrancy chain: deploy an attacker contract whose receive()/fallback() re-enters the target; call the withdrawable function; re-enter before the balance is decremented; repeat until drained. Scaffold: test/attack/AttackerReentrant.sol + a Forge test.

Flash-loan chain: borrow asset X (Aave/Uniswap V3 callback); in the callback manipulate target state (price oracle, reserve ratio, collateral); extract profit; repay loan + fee. Scaffold: FlashLoanAttacker.sol implementing IERC3156FlashBorrower or a Uniswap V3 flash callback.

Delegatecall-overwrite chain: find an unprotected delegatecall to a caller-controlled address; supply a malicious implementation that overwrites slot 0 (owner/admin); call a privileged function. Scaffold: a Forge fuzz test supplying arbitrary impl_addr.

Proxy-upgrade chain: find a UUPS/Transparent proxy with a bypassable upgrade guard (missing onlyOwner, missing _authorizeUpgrade override); upgradeTo(malicious_impl); drain from the new implementation. Scaffold: a Forge test with a MaliciousImpl.

Chain primitives — Solana

CPI privilege-escalation chain: find an instruction that makes a CPI with caller-controlled signer_seeds; derive a PDA whose seeds match a privileged authority; call with the crafted seeds so the program signs on that authority's behalf. Scaffold: a Trident FuzzInstruction supplying crafted seed arrays, or a LiteSVM test.

Account-substitution chain: find an instruction accepting a generic AccountInfo for a privileged account type; pass a different account that passes owner/discriminator checks due to missing validation. Scaffold: a LiteSVM test passing a crafted account buffer.

SPL-arithmetic-overflow chain: find token arithmetic without a checked_* guard; supply an amount that overflows to a small number; withdraw more than deposited. Scaffold: a LiteSVM test with amount = u64::MAX.

Order of ops

1. Map the chain head — the first externally-callable function/instruction the attacker controls.
2. Select the primitive from the categories above and its scaffold.
3. Author the attack contract/test in test/attack/ (Forge) or a programs/attacker/ / fuzz target (Solana). Validate with forge test --match-contract <Attacker> -vvvv, or cargo test / trident fuzz run <target> / cargo fuzz run <target> for Solana.
4. Gate on state confirmation — the chain is valid only if the final state demonstrates the intended impact (balance drain, ownership change, unauthorized state write). Add explicit assertions on the expected final state; a passing test with unclear impact is not a finding.
5. Document the chain — entry point → numbered intermediate steps → final impact → preconditions (flash loan available, specific contract state, fork block). This becomes the PoC evidence handed to impact-validator.

When to pivot

• Chain needs live mainnet state: use forge test --fork-url <rpc> --fork-block-number <n>; never submit a finding that only reproduces on a live fork without documenting the fork block and contract state.
• Chain spans multiple blocks: use vm.warp() / vm.roll() (EVM) or advance slots on a local validator (Solana); document the required delta.

Anti-patterns

• Do NOT author chains that require compromised admin keys or any attacker-unestablishable precondition — out of scope for smart-contract auditing.
• Do NOT submit a chain that only works against a specific past chain state without noting the block-height constraint.
• Do NOT conflate a theoretical chain with a demonstrated one — the Forge/LiteSVM/Trident test must actually pass.
• Do NOT invoke dead tool_wrappers names (forge_test, litesvm_test, trident_fuzz); use the native CLIs above.

Example

// test/attack/ReentrancyAttacker.sol
contract ReentrancyAttacker {
    VulnerableVault vault;
    constructor(address _vault) { vault = VulnerableVault(_vault); }
    function attack() external payable {
        vault.deposit{value: msg.value}();
        vault.withdraw();
    }
    receive() external payable {
        if (address(vault).balance > 0) vault.withdraw(); // re-enter before balance update
    }
}

forge test --match-contract ReentrancyAttacker -vvvv

Recording (chrono-vault)

The task packet's injected memory contract owns the exact call shape, sequence, and fields - see wirework-reflect. Do not copy a record(...) example or add fields (including source_task) from memory; the server binds them, and a baked example violates the run's authenticated schema. Memory is best-effort telemetry and never gates the work. What is worth recording here is the task-specific outcome: chain primitive, entry point, numbered steps, impact, preconditions, test file, reproduced?.