CVE-2018-17071

18.09.2018, 21:29

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.

PRNG

Provider	Type	Base Score	Atk. Vector	Atk. Complexity	Priv. Required	Vector
NIST	NIST	7.5 HIGH	NETWORK	LOW	NONE	CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
mitre	CNA	---				---
CVE	ADP	---				---

Base Score

CVSS 3.x

EPSS Score

Percentile: 54%

Vendor	Product	Version
lucky9	lucky9io	-

𝑥

= Vulnerable software versions

Known Exploits!

Common Weakness Enumeration

CWE-338 - Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)
The product uses a Pseudo-Random Number Generator (PRNG) in a security context, but the PRNG's algorithm is not cryptographically strong.

References

https://github.com/TEAM-C4B/CVE-LIST/tree/master/CVE-2018-17071