PT-2021-23873 · Stark Bank · Ecdsa-Dotnet+4

Published 2021-11-09 · Updated 2022-05-24 · CVE-2021-43568

Positive Technologies (AI Summary)

CVSS v3.1

9.8

Critical

Base vector

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

Name of the Vulnerable Software and Affected Versions Stark Bank Elixir ECDSA library (ecdsa-elixir) version 1.0.0 ecdsa-python versions prior to 2.0.1 ecdsa-java versions prior to 1.0.1 ecdsa-dotnet versions prior to 1.3.2 ecdsa-node versions prior to 1.1.3

Description The verify function in the Stark Bank ECDSA libraries fails to check that the signature is non-zero, allowing attackers to forge signatures on arbitrary messages. This may allow attackers to authenticate as any user within the Stark Bank platform and bypass signature verification needed to perform operations on the platform, such as sending payments and transferring funds. The libraries have around 16k weekly downloads for the ecdsa-node implementation and over 7.3M downloads in the last 90 days on PyPI for the Python implementation. The vulnerability affects the ECDSA signature verification functions, which fail to perform the first check, ensuring that the r and s components of the signatures are in the correct range.

Recommendations For ecdsa-elixir version 1.0.0, update to version 1.0.1 or later. For ecdsa-python versions prior to 2.0.1, update to version 2.0.1 or later. For ecdsa-java versions prior to 1.0.1, update to version 1.0.1 or later. For ecdsa-dotnet versions prior to 1.3.2, update to version 1.3.2 or later. For ecdsa-node versions prior to 1.1.3, update to version 1.1.3 or later.

Exploit

Fix

Improper Verification of Cryptographic Signature

Weakness Enumeration

CWE-347

Related Identifiers

CVE-2021-43568

GHSA-XX36-6RV4-GJ8R

Affected Products

Ecdsa-Dotnet

Ecdsa-Elixir

Ecdsa-Java

Ecdsa-Node

Python-Ecdsa

References · 9

• 🔥 https://research.nccgroup.com/2021/11/08/technical-advisory-arbitrary-signature-forgery-in-stark-bank-ecdsa-libraries · Exploit
• https://osv.dev/vulnerability/GHSA-xx36-6rv4-gj8r · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2021-43568 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2021-43568 · Security Note
• https://github.com/starkbank/ecdsa-elixir/releases/tag/v1.0.1 · Note
• https://github.com/starkbank/ecdsa-elixir · Note
• https://github.com/starkbank/ecdsa-elixir/commit/a5168f6d9cfbe0a0a62d92e2e9b1a97235d90343 · Note
• https://github.com/starkbank/ecdsa-elixir/commit/4b960e26768bb698f449eb7686b5664936b70b61 · Note
• https://t.me/cibsecurity/32124 · Telegram Post