Vulnerabilities > CVE-2018-17071 - Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG) vulnerability in Lucky9 Lucky9Io
Attack vector
NETWORK Attack complexity
LOW Privileges required
NONE Confidentiality impact
PARTIAL Integrity impact
NONE Availability impact
NONE Summary
The fallback function of a simple lottery smart contract implementation for Lucky9io, an Ethereum gambling game, generates a random value with the publicly readable variable entry_number. This variable is private, yet it is readable by eth.getStorageAt function. Also, attackers can purchase a ticket at a low price by directly calling the fallback function with small msg.value, because the developer set the currency unit incorrectly. Therefore, it allows attackers to always win and get rewards.
Vulnerable Configurations
| Part | Description | Count |
|---|---|---|
| Application | 1 |