CVE-2021-43571 in ecdsa-node
Summary
by MITRE • 11/10/2021
The verify function in the Stark Bank Node.js ECDSA library (ecdsa-node) 1.1.2 fails to check that the signature is non-zero, which allows attackers to forge signatures on arbitrary messages.
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Analysis
by VulDB Data Team • 11/12/2021
The vulnerability identified as CVE-2021-43571 resides within the Stark Bank Node.js ECDSA library version 1.1.2 where the verify function demonstrates a critical cryptographic flaw by failing to validate that the signature is non-zero. This weakness represents a fundamental failure in the library's signature verification process that directly undermines the security guarantees of the elliptic curve digital signature algorithm. The issue stems from the absence of proper signature validation checks that should ensure the signature components meet the mathematical requirements for valid ECDSA signatures. According to CWE-330, this vulnerability aligns with insufficient entropy or validation flaws in cryptographic implementations, where the failure to properly validate signature components creates an exploitable condition.
The technical flaw manifests when an attacker can craft a signature that passes the verification routine despite being mathematically invalid, specifically by creating a zero signature value that bypasses the necessary cryptographic checks. This vulnerability operates at the core of the cryptographic verification process and represents a failure in the library's adherence to established cryptographic standards and best practices. The absence of zero signature validation creates a condition where forged signatures can appear legitimate to the verification function, thereby undermining the integrity of the entire digital signature system. This type of vulnerability falls under the ATT&CK technique T1556.004 for credential manipulation and can be classified as a cryptographic weakness in the context of the MITRE ATT&CK framework for adversary tactics and techniques.
The operational impact of this vulnerability is severe and far-reaching for any system relying on the affected Stark Bank Node.js ECDSA library for signature verification. Attackers can exploit this weakness to forge digital signatures on arbitrary messages, potentially compromising the authenticity and integrity of digital communications, transactions, and data exchanges that depend on ECDSA for security. Systems that utilize this library for validating user credentials, transaction authenticity, or document signatures become vulnerable to malicious actors who can create fraudulent signatures that will be accepted as legitimate by the verification process. The consequences extend beyond simple credential compromise to include potential financial fraud, data manipulation, and unauthorized access to protected systems.
Organizations using the affected library must implement immediate mitigations to address this vulnerability. The primary remediation involves upgrading to a patched version of the ecdsa-node library where the signature verification process properly validates that signature components are non-zero and meet the mathematical requirements for valid ECDSA signatures. Additionally, system administrators should conduct comprehensive audits of all applications that rely on this library to identify potential attack vectors and ensure that proper signature validation is implemented across all cryptographic operations. Security teams should also consider implementing additional monitoring and logging of signature verification activities to detect potential exploitation attempts and establish incident response procedures for handling signature forgery incidents. The vulnerability highlights the critical importance of proper cryptographic implementation and validation, emphasizing that even minor oversights in signature verification can lead to catastrophic security failures.