CVE-2016-6298 in jwcrypto
Summary
by MITRE
The _Rsa15 class in the RSA 1.5 algorithm implementation in jwa.py in jwcrypto before 0.3.2 lacks the Random Filling protection mechanism, which makes it easier for remote attackers to obtain cleartext data via a Million Message Attack (MMA).
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Analysis
by VulDB Data Team • 11/01/2024
The vulnerability identified as CVE-2016-6298 resides within the jwcrypto library's implementation of the RSA 1.5 algorithm, specifically in the _Rsa15 class located in the jwa.py file. This flaw represents a critical security weakness that directly impacts the cryptographic protection mechanisms designed to safeguard sensitive data during encryption operations. The issue affects versions prior to 0.3.2 of the jwcrypto library, which is widely used for implementing JSON Web Encryption (JWE) and JSON Web Signature (JWS) standards in web applications and services.
The core technical flaw stems from the absence of Random Filling protection within the RSA 1.5 implementation. This protection mechanism is essential for preventing certain types of cryptographic attacks that exploit predictable patterns in encrypted data. The RSA 1.5 algorithm, while widely deployed, requires proper padding schemes to ensure security against various attack vectors. Without the Random Filling protection, the encryption implementation becomes vulnerable to mathematical analysis that can reveal information about the plaintext data through carefully crafted attacks. This weakness particularly affects the security guarantees that should be provided by the RSA encryption standard when properly implemented.
The operational impact of this vulnerability is severe and directly relates to the Million Message Attack (MMA) technique that remote attackers can exploit. An MMA allows adversaries to perform a series of encryption requests and analyze the resulting ciphertext patterns to gradually reconstruct the original plaintext data. This attack vector is particularly dangerous because it can be executed remotely without requiring direct access to the encryption keys or the underlying cryptographic infrastructure. The vulnerability essentially provides attackers with a pathway to perform statistical analysis on encrypted communications, potentially leading to the exposure of sensitive information such as user credentials, personal data, or confidential business information. This type of attack aligns with the techniques documented in the ATT&CK framework under credential access and data extraction tactics.
The vulnerability manifests as a weakness in the cryptographic implementation that violates fundamental security principles established by industry standards including the Common Weakness Enumeration (CWE) classification for improper implementation of cryptographic primitives. The lack of proper padding mechanisms in the RSA 1.5 implementation creates a scenario where the encryption process becomes deterministic in ways that should not occur in secure cryptographic systems. This weakness directly impacts the security of any application or service that relies on jwcrypto for encryption operations, particularly those handling sensitive data in web environments where JSON Web Encryption is employed. Organizations using affected versions of jwcrypto should immediately consider upgrading to version 0.3.2 or later to address this vulnerability and prevent potential exploitation by malicious actors.
The mitigation strategy for this vulnerability requires immediate deployment of the patched version of jwcrypto, specifically version 0.3.2 or higher, which includes the necessary Random Filling protection mechanism. Additionally, security teams should conduct comprehensive assessments of all systems utilizing jwcrypto to identify potential exposure windows and implement monitoring for suspicious cryptographic activity patterns. Organizations should also consider implementing additional security controls such as network segmentation, intrusion detection systems, and regular security audits to detect potential exploitation attempts. The vulnerability highlights the critical importance of proper cryptographic implementation and the necessity of following established security standards to prevent the deployment of insecure cryptographic components in production environments.