CVE-2018-12025

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.

• CVE ID
• CVE-2018-12025

• Assigner
• cve@mitre.org

• Vulnerability Status
• Analyzed

• Published Version
• 2018-06-11T10:29:00

• Last Modified Date
• 2018-08-06T16:37:56

• Version
• 2.0

• Vector String
• AV:N/AC:L/Au:N/C:N/I:P/A:N

• Access Vector
• NETWORK

• Access Compatibility
• LOW

• Authentication
• NONE

• Confidentiality Impact
• NONE

• Integrity Impact
• PARTIAL

• Availability Impact
• NONE

• Base Score
• 5

• Severity
• MEDIUM

• Exploitability Score
• 10

• Impact Score
• 2.9

• Version
• 3.0

• Vector String
• CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

• Attack Vector
• NETWORK

• Attack Compatibility
• LOW

• Privileges Required
• NONE

• User Interaction
• NONE

• Scope
• UNCHANGED

• Confidentiality Impact
• NONE

• Availability Impact
• NONE

• Base Score
• 7.5

• Base Severity
• HIGH

• Exploitability Score
• 3.9

• Impact Score
• 3.6