5 Medium
CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
PARTIAL
Availability Impact
NONE
AV:N/AC:L/Au:N/C:N/I:P/A:N
7.5 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
HIGH
Availability Impact
NONE
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
0.001 Low
EPSS
Percentile
38.1%
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.
5 Medium
CVSS2
Attack Vector
NETWORK
Attack Complexity
LOW
Authentication
NONE
Confidentiality Impact
NONE
Integrity Impact
PARTIAL
Availability Impact
NONE
AV:N/AC:L/Au:N/C:N/I:P/A:N
7.5 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
HIGH
Availability Impact
NONE
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
0.001 Low
EPSS
Percentile
38.1%