CVE-2018-12025 Information
Description
The transferFrom function of a smart contract implementation for FuturXE (FXE) an Ethereum ERC20 token allows attackers to accomplish an unauthorized transfer of digital assets because of a logic error. The developer messed up with the boolean judgment - if the input value is smaller than or equal to allowed value the transfer session would stop execution by returning false. This makes no sense because the transferFrom() function should require the transferring value to not exceed the allowed value in the first place. Suppose this function asks for the allowed value to be smaller than the input. Then the attacker could easily ignore the allowance: after this condition the allowed[from][msg.sender] -= value; would cause an underflow because the allowed part is smaller than the value. The attacker could transfer any amount of FuturXe tokens of any accounts to an appointed account (the _to address) because the allowed value is initialized to 0 and the attacker could bypass this restriction even without the victim’s private key.
CVSS Vector
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Reference
Attack Complexity
LOW
Privileges Required
NONE
User Interaction Required
NONE
Scope
NONE
Confidentiality Impact
UNCHANGED
Integrity Impact
NONE
Availability Impact
HIGH
Base Score
NONE
Base Severity
7.5
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