A vulnerability was found in Py-EVM 0.2.0-alpha.33 and classified as critical. This issue affects the function vm.execute_bytecode. The manipulation as part of a Smart Contract leads to a memory corruption vulnerability. Using CWE to declare the problem leads to CWE-119. The product performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

Py-EVM v0.2.0-alpha.33 allows attackers to make a vm.execute_bytecode call that triggers computation._stack.values with '"stack": [100, 100, 0]' where b'\x' was expected, resulting in an execution failure because of an invalid opcode. This is reportedly related to "smart contracts can be executed indefinitely without gas being paid."

The bug was discovered 10/31/2018. The weakness was presented 11/12/2018 (Website). The advisory is shared at github.com. The identification of this vulnerability is CVE-2018-18920 since 11/03/2018. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available.

The vulnerability was handled as a non-public zero-day exploit for at least 11 days. During that time the estimated underground price was around $0-$5k.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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• Py-EVM

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• 0.2.0-alpha.33

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CPE 2.2info

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