GivingThanks

Summary

The updateRegistry function in the GivingThanks contract allows anyone to change the address of the CharityRegistry contract, as it lacks access control. This vulnerability can lead to unauthorized modifications, allowing a malicious user to replace the registry address with their own contract, thus gaining control over which charities are considered valid and potentially redirecting funds to unverified addresses.

Vulnerability Details

The updateRegistry function lacks any access control checks, such as onlyOwner, allowing any caller to change the registry address to an arbitrary one:

Without restrictions, any user can call updateRegistry, effectively replacing the CharityRegistry address. This enables a malicious user to:

• Redirect donations to unverified addresses.

• Manipulate the verification logic by introducing a registry that might approve any address as a "verified charity."

Impact

This vulnerability poses a severe security risk:

• Unauthorized Modification of Critical Contract Logic: By replacing the registry, a malicious user can modify which addresses are considered verified, which can lead to unauthorized redirection of donations.

• Financial Exploitation: The attacker could direct funds to a fake charity registry and mark arbitrary addresses as "verified," receiving unauthorized donations.
  Tools Used

Recommendations

Implement Access Control: Restrict access to updateRegistry by adding an access control modifier, such as onlyOwner, to ensure that only the contract owner can update the registry address.