CVE-2016-1000342 in JCE Provider
Summary
by MITRE
In the Bouncy Castle JCE Provider version 1.55 and earlier ECDSA does not fully validate ASN.1 encoding of signature on verification. It is possible to inject extra elements in the sequence making up the signature and still have it validate, which in some cases may allow the introduction of 'invisible' data into a signed structure.
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Analysis
by VulDB Data Team • 05/12/2025
The vulnerability identified as CVE-2016-1000342 affects the Bouncy Castle JCE Provider version 1.55 and earlier implementations, specifically targeting the ECDSA signature verification process. This flaw represents a critical weakness in the cryptographic validation mechanism that could potentially undermine the integrity of digital signatures. The issue stems from insufficient validation of ASN.1 encoding structures during the signature verification phase, creating an avenue for malicious manipulation of signature data.
The technical flaw manifests in the improper handling of ASN.1 sequence structures within ECDSA signatures. When verifying signatures, the Bouncy Castle provider fails to conduct thorough validation of the complete ASN.1 encoding structure, allowing attackers to inject additional elements into the signature sequence without breaking the verification process. This behavior violates fundamental cryptographic principles where signature verification should be strict and reject any deviations from the expected format. The vulnerability specifically affects the parsing logic that processes the r and s components of ECDSA signatures, which are encoded as integers within an ASN.1 sequence structure.
The operational impact of this vulnerability extends beyond simple signature validation failures, potentially enabling sophisticated attacks that could compromise the security of cryptographic systems relying on Bouncy Castle. Attackers could exploit this weakness to inject hidden data into signed structures, creating what are essentially "invisible" modifications that would pass validation checks while altering the underlying signed content. This capability could be particularly dangerous in applications where digital signatures are used for integrity protection, authentication, or non-repudiation purposes, as it undermines the fundamental trust model that digital signatures are designed to provide.
This vulnerability aligns with CWE-295, which addresses improper certificate validation, and demonstrates characteristics similar to those found in CWE-327, concerning weak cryptographic algorithms. The flaw also relates to ATT&CK technique T1552.004, which involves the use of cryptographic protocols to bypass security controls, and T1059.001, which encompasses the manipulation of signature validation processes. The issue represents a classic case of incomplete input validation where the system accepts malformed but technically valid ASN.1 structures that should be rejected during cryptographic verification.
Organizations using affected versions of Bouncy Castle should immediately upgrade to version 1.56 or later, where the ASN.1 validation has been properly implemented. Additionally, security teams should conduct comprehensive audits of all systems utilizing Bouncy Castle for cryptographic operations, particularly those handling sensitive digital signatures. The mitigation strategy should include implementing additional signature validation layers that independently verify ASN.1 structures, establishing monitoring for unusual signature patterns, and ensuring that all cryptographic operations undergo rigorous testing against known attack vectors. System administrators should also consider implementing signature validation policies that enforce strict ASN.1 structure compliance and maintain detailed logging of all signature verification activities for forensic analysis purposes.