GivingThanks
First Flight #28
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Submission Details
Severity: high
Valid

Unverified Charities Can Receive Donations Due to Incorrect Verification Logic

chrissavov

Summary

The GivingThanks contract allows donations to charities that are registered but not verified, bypassing the intended verifyCharity requirement. This occurs due to a logic flaw in the isVerified function in CharityRegistry, which incorrectly checks the registeredCharities mapping instead of verifiedCharities.

Vulnerability Details

  1. Root Cause: In the GivingThanks contract, the donate function checks charity verification status via registry.isVerified(charity). However, in CharityRegistry, the isVerified function returns true for any registered charity, even if it’s not verified.

  2. Expected Behavior: Only charities that are both registered and verified should pass the isVerified check in donate.

  3. Current Behavior: Any registered charity (even unverified ones) will pass the isVerified check, allowing donations to potentially untrusted recipients.

Impact

This vulnerability enables donations to charities that have not been vetted by the intended verifyCharity process, undermining the verification requirement and allowing unverified charities to receive funds. This could lead to potential misallocation of donated funds or abuse by malicious actors registering as charities without undergoing verification.

Tools Used

Manual code review, Foundry

Recommendations

  1. Update isVerified Logic: Modify isVerified in CharityRegistry to return true only if the charity is verified by checking verifiedCharities[charity]:

    function isVerified(address charity) public view returns (bool) {
    - return registeredCharities[charity];
    + return verifiedCharities[charity];
    }

POC

Running the line forge test -mt testCannotDonateToUnverifiedCharity with the following set up and test functions:

function setUp() public {
// Initialize addresses
admin = makeAddr("admin");
charity = makeAddr("charity");
donor = makeAddr("donor");
​
// Deploy the CharityRegistry contract as admin
vm.prank(admin);
registryContract = new CharityRegistry();
​
// Deploy the GivingThanks contract by making it appear as if CharityRegistry is the deployer
vm.prank(address(registryContract));
charityContract = new GivingThanks(address(registryContract));
​
// Register and verify the charity
vm.prank(admin);
registryContract.registerCharity(charity);
​
vm.prank(admin);
registryContract.verifyCharity(charity);
}
​
function testCannotDonateToUnverifiedCharity() public {
address unverifiedCharity = address(0x4);
​
// Unverified charity registers but is not verified
vm.prank(unverifiedCharity);
registryContract.registerCharity(unverifiedCharity);
​
// Fund the donor
vm.deal(donor, 10 ether);
​
// Donor tries to donate to unverified charity
vm.prank(donor);
vm.expectRevert();
charityContract.donate{value: 1 ether}(unverifiedCharity);
}

will output

Ran 1 test for test/GivingThanks.t.sol:GivingThanksTest
[FAIL: next call did not revert as expected] testCannotDonateToUnverifiedCharity() (gas: 307609)
Suite result: FAILED. 0 passed; 1 failed; 0 skipped; finished in 923.48µs (243.06µs CPU time)

This test demonstrates that a donor may make a donation to a unregistered charity.

Updates

Lead Judging Commences

n0kto Lead Judge 12 months ago
Submission Judgement Published
Validated
Assigned finding tags:

finding-isVerified-return-registered-charities

Likelyhood: High, the function returns registered charities instead of verified ones. Impact: High, Any charities can be registered by anyone and will be declared as verified by this function bypassing verification.

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