PT-2023-21717 · Frontier+2 · Frontier+2

Guidovranken · Published 2023-03-21 · Updated 2023-03-28 · CVE-2023-28431

Positive Technologies (AI Summary)

CVSS v3.1

7.5

High

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Name of the Vulnerable Software and Affected Versions Frontier versions prior to the deployment of pull request 1017

Description The issue arises from the modexp precompile in Frontier, which uses the num-bigint crate. The implementation treats odd and even moduli differently, with odd moduli using fast Montgomery multiplication and even moduli using the slow plain power algorithm. This discrepancy in gas costs was not accounted for, potentially leading to denial of service attacks. There are no known instances of this issue being exploited in real-world attacks.

Recommendations

• If you anticipate malicious validators, issue an emergency runtime upgrade as soon as possible.
• If you do not anticipate malicious validators, issue a normal runtime upgrade, as Substrate has built-in timeout protection when validators are building blocks.
• Consider raising the gas costs for even modulus as a short-term fix until a long-term solution is implemented in num-bigint or by switching to another modexp implementation.

Exploit

Fix

Weakness Enumeration

CWE-682

Related Identifiers

CVE-2023-28431

GHSA-FCMM-54JP-7VF6

Affected Products

Frontier

Substrate

Num-Bigint

References · 9

• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/28xxx/CVE-2023-28431.json · Exploit
• https://github.com/paritytech/frontier/security/advisories/GHSA-fcmm-54jp-7vf6 · Vendor Advisory
• https://github.com/paritytech/frontier/commit/5af12e94d7dfc8a0208a290643a800f55de7b219 · Patch
• https://github.com/paritytech/frontier/pull/1017 · Patch
• https://osv.dev/vulnerability/GHSA-fcmm-54jp-7vf6 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2023-28431 · Security Note
• https://osv.dev/vulnerability/CVE-2023-28431 · Vendor Advisory
• https://github.com/polkadot-evm/frontier · Note
• https://github.com/rust-num/num-bigint/blob/6f2b8e0fc218dbd0f49bebb8db2d1a771fe6bafa/src/biguint/power.rs#L134 · Note