status is by default Nice for users has not passed checkList function
Summary
In checkTwice function, an unsafe check is used to detect user's status in first check.
Vulnerability Details
If s_theListCheckedOnce does not have a key of certain address, s_theListCheckedOnce[person] by default equals 0. In enum Status, NICE is also equal to 0. Thus, all addresses not in s_theListCheckedOnce has a status of NICE by default.
Impact
checkTwice function can assign s_theListCheckedTwice[address] to NICE for those addresses not a key in s_theListCheckedOnce
Tools Used
Foundry
Recommendations
change the first element in enum Status to be "UNKOWN" instead of "NICE"
Lead Judging Commences
default status is nice
In Solidity the first element of an enum is the default value. In Santa's List, the means each person is mapped by default to 'NICE'.
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