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The random() function of the smart contract implementation for CryptoSaga, an Ethereum game, generates a random value with publicly readable variables such as timestamp, the current block's blockhash, and a private variable (which can be read with a getStorageAt call). Therefore, attackers can precompute the random number and manipulate the game (e.g., get powerful characters or get critical damages).
The random() function of the smart contract implementation for CryptoSaga, an Ethereum game, generates a random value with publicly readable variables such as timestamp, the current block's blockhash, and a private variable (which can be read with a getStorageAt call). Therefore, attackers can precompute the random number and manipulate the game (e.g., get powerful characters or get critical damages).
CVSS 3.0 Base Score 7.5. CVSS Attack Vector: network. CVSS Attack Complexity: low. CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).
CVSS 2.0 Base Score 5. CVSS Attack Vector: network. CVSS Attack Complexity: low. CVSS Vector: (AV:N/AC:L/Au:N/C:P/I:N/A:N).
Both of these examples use a statistical PRNG to generate a random number:
int accountID = random.nextInt();
int randNum = rand();The random number functions used in these examples, rand() and Random.nextInt(), are not considered cryptographically strong. An attacker may be able to predict the random numbers generated by these functions. Note that these example also exhibit CWE-337 (Predictable Seed in PRNG).
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