CVE Vulnerabilities

CVE-2018-12025

Integer Underflow (Wrap or Wraparound)

Published: Jun 11, 2018 | Modified: Aug 06, 2018
CVSS 3.x
7.5
HIGH
Source:
NVD
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
CVSS 2.x
5 MEDIUM
AV:N/AC:L/Au:N/C:N/I:P/A:N
RedHat/V2
RedHat/V3
Ubuntu

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 victims private key.

Weakness

The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.

Affected Software

Name Vendor Start Version End Version
Futurxe Futurxe - -

References