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web3-case-study-role-misconfig
// Case study - role misconfiguration bug class applied to a yield aggregator protocol. Use as a template for applying all 10 bug classes to a single target.
// Case study - role misconfiguration bug class applied to a yield aggregator protocol. Use as a template for applying all 10 bug classes to a single target.
[HINT] Download the complete skill directory including SKILL.md and all related files
| name | web3-case-study-role-misconfig |
| description | Case study - role misconfiguration bug class applied to a yield aggregator protocol. Use as a template for applying all 10 bug classes to a single target. |
| Contains | architecture walkthrough, all bug class verdicts, 2 findings (DISTRIBUTOR_ROLE never granted, dust harvest DoS), complete PoC templates, report drafts, validation steps. |
Bug Class: Access Control | Severity: Critical/Medium | Payout Range: $10K–$50K This file shows how to apply the full 10-class methodology to a real yield aggregator target.
| Field | Value |
|---|---|
| Protocol Type | Yield aggregator — stablecoin → lending protocol → harvest → DEX → reward token |
| Max Bounty | $50K (Critical) |
| TVL | Low (fresh program, under $100K) |
| Core Contracts | Vault.sol, RewardsDistributor.sol |
| Program Age | ~5 days when hunted (fresh = low competition) |
| Prior Audits | Firm A (16 findings, all Risk Accepted) + Firm B (18 findings, all Risk Accepted) |
Scorecard: Max bounty (+2) + custom math (+1) + recent code (+1) + known prior audits (+1) + public source (+1) + program new (+2) = 8/10 → HUNT
Why this scores high: Fresh program on a live bounty platform + prior audits that accepted all risk = team is aware of issues but hasn't patched them. Hunt for what auditors missed or flagged but accepted.
User deposits Stablecoin
↓ deposit(uint256 amount)
Vault.sol stores:
- deposits[user] += amount
- totalDeposited += amount
- depositTimestamp[user] = block.timestamp
↓ safeTransferFrom(user, address(this), amount)
↓ lendingProtocol.supply(stablecoin, amount, address(this), 0)
Interest-bearing token accrues in Vault.sol balance
↓ (periodic) _performHarvest()
aToken balance > totalDeposited + DUST_THRESHOLD
↓ lendingProtocol.withdraw(stablecoin, harvestAmount - 1, address(this))
↓ dex.exactInputSingle(stablecoin → rewardToken)
↓ RewardsDistributor.distribute(rewardToken, amount)
RewardsDistributor tracks:
- cumulativeRewardPerShare updates
- users can call claimFor(user) to collect rewardToken
User withdraws:
↓ withdraw(uint256 amount)
if block.timestamp < depositTimestamp[user] + LOCK_PERIOD:
withdrawFee applies (e.g. 0.5%)
lendingProtocol.withdraw(stablecoin, amount, user)
Key state variables:
deposits[user] — user principal (stablecoin)totalDeposited — sum of all principalsdepositTimestamp[user] — last deposit time (affects withdrawal fee)cumulativeRewardPerShare — reward index in RewardsDistributorlastClaimedReward[user] — user's last reward indexAll standard: missing events, gas optimizations, reentrancy guards present (CEI followed), centralization risks (owner can pause), single oracle (DEX swap is operational, not security-critical).
Including:
Pattern: Firm B flagged "missing check" but didn't verify the role was actually ungranted. This is the gap to exploit.
Finding 1: The -1 Stranding Pattern
// In _performHarvest():
harvestAmount = aToken.balanceOf(address(this)) - totalDeposited - 1; // strands 1 wei
The hardcoded -1 strands 1 wei of stablecoin per harvest permanently. Over thousands of harvests, this accumulates. Severity: LOW/INFORMATIONAL (no user loss, just protocol dust accumulation).
Finding 2: Dust Harvest DoS ← VALID MEDIUM
Scenario: Accumulated harvest amount is very tiny (< DEX minimum swap)
1. harvest() calls dex.exactInputSingle(stablecoin → rewardToken)
2. DEX returns 0 (amount too small to produce any output)
3. RewardsDistributor.distribute(0) is called
4. If distribute() reverts on 0 amount → harvest is permanently frozen
5. Users can still withdraw principal but all future yield is lost
Verification: Check if distribute(0) reverts. Check DEX minimum swap threshold.
Finding: DISTRIBUTOR_ROLE Never Granted ← MAIN FINDING
// RewardsDistributor.sol
bytes32 public constant DISTRIBUTOR_ROLE = keccak256("DISTRIBUTOR_ROLE");
function claimFor(address user) external {
require(hasRole(DISTRIBUTOR_ROLE, msg.sender), "Not distributor");
// ... distribute rewardToken to user
}
Problem: DISTRIBUTOR_ROLE is defined but NEVER granted in the constructor or any initialization function. No address holds this role. claimFor() can never succeed — all reward tokens are permanently locked.
How Firm B missed it: They flagged "missing check for whether role is set" — but their fix recommendation was "add a require that checks the role exists." They didn't verify that getRoleMemberCount(DISTRIBUTOR_ROLE) == 0 on the live deployment.
Severity Assessment:
Verification commands:
# Check if any address has DISTRIBUTOR_ROLE (replace with actual address)
cast call <REWARDS_DISTRIBUTOR_ADDR> \
"getRoleMemberCount(bytes32)(uint256)" \
"$(cast keccak 'DISTRIBUTOR_ROLE')"
# Expected: 0 = confirmed bug
# Alternative: Etherscan → Events → filter "RoleGranted"
# If no RoleGranted events with DISTRIBUTOR_ROLE hash = confirmed
Firm B HAL-05: deposit() resets depositTimestamp[user] even on partial top-ups, extending the lock period for all existing deposits. Risk Accepted by team.
All boundary operators (>=, <) in Vault.sol and RewardsDistributor.sol are correct.
Protocol does NOT use price oracles for security decisions (no lending, no liquidation, no collateral). The DEX swap is operational (converting yield), not security-critical. MEV/sandwich risk exists but is a griefing/efficiency issue, not a theft vulnerability.
Uses a custom 1:1 share model, NOT ERC4626:
deposits[user] tracks exact principalFollows CEI (Checks-Effects-Interactions) correctly:
deposits[user] += amount BEFORE lendingProtocol.supply()deposits[user] -= amount BEFORE lendingProtocol.withdraw()nonReentrant guard, but CEI makes it safe. Not submittable without PoC.Flash loan attack would attempt: deposit → dilute harvest → withdraw to steal yield.
The withdrawFee makes this unprofitable:
No signature-based functions, no EIP-2612 permit, no meta-transactions.
Not upgradeable proxies. No proxy pattern.
Finding 1 — CRITICAL/HIGH:
Title: DISTRIBUTOR_ROLE never granted in RewardsDistributor.sol,
permanently locking all reward tokens
Root Cause: DISTRIBUTOR_ROLE is defined but grantRole() is never called
in constructor or initialization. No address holds this role.
Impact: All rewards distributed by harvest() are permanently locked —
claimFor() always reverts.
Users receive zero yield despite depositing and paying withdrawFee.
Attack Path: Not an attack — passive failure. Any harvest → rewards locked forever.
Severity: Critical (if harvest has occurred) / High (if not yet)
Finding 2 — MEDIUM:
Title: _performHarvest() dust harvest causes permanent DoS on yield distribution
Root Cause: When accumulated yield rounds to < DEX minimum swap amount,
exactInputSingle() returns 0 output. distribute(0) may revert or
permanently advance the reward index with no rewards.
Impact: After a dust harvest, all subsequent harvests may fail permanently.
Severity: Medium (requires specific conditions but permanently impacts yield)
-1 stranding (informational, design choice)// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.13;
import "forge-std/Test.sol";
import "forge-std/console.sol";
interface IRewardsDistributor {
function DISTRIBUTOR_ROLE() external view returns (bytes32);
function hasRole(bytes32 role, address account) external view returns (bool);
function getRoleMemberCount(bytes32 role) external view returns (uint256);
function claimFor(address user) external;
}
contract RoleNeverGrantedTest is Test {
// Replace with actual deployed address from target
address constant REWARDS_DISTRIBUTOR = address(0xYOUR_TARGET_ADDRESS);
IRewardsDistributor distributor;
function setUp() public {
// Fork at current block
vm.createSelectFork(vm.envString("MAINNET_RPC_URL"));
distributor = IRewardsDistributor(REWARDS_DISTRIBUTOR);
}
function testDistributorRoleNeverGranted() public {
bytes32 DISTRIBUTOR_ROLE = distributor.DISTRIBUTOR_ROLE();
uint256 memberCount = distributor.getRoleMemberCount(DISTRIBUTOR_ROLE);
console.log("Addresses with DISTRIBUTOR_ROLE:", memberCount);
// Should be 0 — proving no one can call claimFor()
assertEq(memberCount, 0, "DISTRIBUTOR_ROLE has 0 members (confirmed bug)");
// Verify claimFor() reverts for any user
address testUser = address(0x1234);
vm.expectRevert(); // "AccessControl: account does not have role"
distributor.claimFor(testUser);
console.log("CONFIRMED: claimFor() reverts for all users.");
console.log("All rewards permanently locked.");
}
}
Run:
forge test --match-test testDistributorRoleNeverGranted -vvvv \
--fork-url $MAINNET_RPC_URL
Expected output:
Addresses with DISTRIBUTOR_ROLE: 0
CONFIRMED: claimFor() reverts for all users.
All rewards permanently locked.
[PASS] testDistributorRoleNeverGranted()
Title: Missing DISTRIBUTOR_ROLE grant permanently locks all rewards for all users
Bug Description:
RewardsDistributor.sol defines DISTRIBUTOR_ROLE and requires it to call claimFor(). However, grantRole(DISTRIBUTOR_ROLE, ...) is never called in the constructor, any initialization function, or any privileged setter. No address holds this role. claimFor() always reverts.
The Vault contract calls RewardsDistributor.distribute() after each harvest, successfully depositing reward tokens into the distributor. However, these tokens can never be claimed — permanently locked.
Root Cause: Constructor is missing grantRole(DISTRIBUTOR_ROLE, vaultContract).
Impact: All yield earned by all depositors is permanently locked in RewardsDistributor.sol. Users cannot receive any return from their deposits.
Impact category: Permanent freezing of funds
Proof of Concept: [Run PoC above against deployed contract]
Remediation: Add grantRole(DISTRIBUTOR_ROLE, address(vault)) in RewardsDistributor constructor, OR add a setDistributor(address) function callable only by admin.
| Question | DISTRIBUTOR_ROLE | Dust Harvest DoS |
|---|---|---|
| Can attacker use it NOW? | Yes (passive — already locked) | Yes (needs small harvest) |
| Impact in program's list? | Permanent freezing of funds ✓ | Temporary/permanent DoS ✓ |
| In-scope contract? | RewardsDistributor.sol ✓ | Vault.sol ✓ |
| Requires admin access? | No — passive ✓ | No — anyone can trigger ✓ |
| Already known/acknowledged? | No ✓ | No ✓ |
| Economically viable? | Yes — passive lock ✓ | Yes — dust accumulates ✓ |
| Already public? | No ✓ | No ✓ |
| VERDICT | SUBMIT | SUBMIT |
This pattern (role defined, never granted) appears frequently in:
bytes32 public constant *_ROLE — verify each one has a corresponding grantRole() call in constructorGrep to find candidates:
# Find all role definitions
grep -r "bytes32 public constant.*ROLE" ./src/
# Verify each role has a grantRole call
grep -r "grantRole" ./src/
# If roles > grantRole calls → investigate each missing grant
Protocols to check for this pattern: Any protocol where RewardsDistributor, FeeDistributor, YieldDistributor, or Distributor is a separate contract from the main vault.
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