CVE-2020-12118 in tss-lib
Summary
by MITRE
The keygen protocol implementation in Binance tss-lib before 1.2.0 allows attackers to generate crafted h1 and h2 parameters in order to compromise a signing round or obtain sensitive information from other parties.
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Analysis
by VulDB Data Team • 06/02/2024
The vulnerability identified as CVE-2020-12118 resides within the threshold signature scheme library used by Binance's tss-lib implementation prior to version 1.2.0. This issue fundamentally impacts the cryptographic security of distributed signing operations that rely on the key generation protocol. The flaw enables malicious actors to manipulate the h1 and h2 parameters during the key generation phase, which are critical components in threshold signature schemes that require multiple parties to collaboratively generate a valid signature without any single party possessing the complete private key.
The technical implementation flaw stems from insufficient validation and sanitization of parameters during the key generation protocol execution. In threshold signature schemes, h1 and h2 represent specific mathematical values that must be carefully computed and verified to maintain cryptographic integrity. When these parameters are not properly validated, attackers can inject crafted values that disrupt the normal signing process. This vulnerability falls under the category of improper input validation and weak cryptographic implementation as classified by CWE-20. The attack vector specifically targets the key generation phase where multiple parties contribute to create the distributed key pair, making it a critical point of failure in the security architecture.
The operational impact of this vulnerability extends beyond simple cryptographic weakness to potentially compromise entire distributed signing operations within the Binance ecosystem. When attackers can manipulate h1 and h2 parameters, they gain the ability to either force a signing round to fail or to extract sensitive information from participating parties. This could lead to complete compromise of the threshold signature scheme, allowing unauthorized parties to generate valid signatures without proper authorization. The vulnerability particularly affects multi-party computation environments where trust is distributed among multiple participants, as it undermines the fundamental security assumptions of such systems. According to ATT&CK framework, this vulnerability maps to T1552.001 - Credentials in Files and T1552.006 - Steal or Forge Certificates, as it enables credential compromise through cryptographic manipulation.
The security implications of CVE-2020-12118 are particularly severe in blockchain and cryptocurrency environments where threshold signatures are commonly used for wallet security and transaction validation. This vulnerability could enable attackers to gain unauthorized access to funds by compromising the signing process or to extract private key components from participating parties. The attack could result in complete loss of funds or unauthorized transactions on the blockchain. Organizations using Binance tss-lib prior to version 1.2.0 should immediately implement mitigation strategies including upgrading to the patched version, implementing additional parameter validation checks, and monitoring for suspicious signing activities. The vulnerability demonstrates the critical importance of proper cryptographic protocol implementation and the need for thorough security testing of threshold signature schemes in distributed environments.