CVE-2018-25099 in CryptX
Summary
by MITRE • 03/18/2024
In the CryptX module before 0.062 for Perl, gcm_decrypt_verify() and chacha20poly1305_decrypt_verify() do not verify the tag.
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Analysis
by VulDB Data Team • 03/14/2025
The vulnerability identified as CVE-2018-25099 resides within the CryptX Perl module, specifically affecting versions prior to 0.062. This issue impacts two critical cryptographic functions: gcm_decrypt_verify() and chacha20poly1305_decrypt_verify(). The flaw represents a fundamental breakdown in the authentication mechanism of these encryption routines, where the cryptographic tag verification process is completely omitted during decryption operations. This omission creates a severe security weakness that undermines the integrity and authenticity guarantees that these authenticated encryption modes are designed to provide.
The technical nature of this vulnerability stems from the failure to validate the authentication tag that is typically generated and verified as part of the authenticated encryption process. In Galois/Counter Mode (GCM) and ChaCha20-Poly1305 encryption schemes, the authentication tag serves as a cryptographic proof that the ciphertext has not been tampered with and that it originated from a legitimate source. When the gcm_decrypt_verify() and chacha20poly1305_decrypt_verify() functions skip this verification step, they effectively disable the integrity protection mechanism. This allows an attacker to modify ciphertext without detection, potentially leading to successful decryption of tampered data without any error indication. The vulnerability directly maps to CWE-310, which addresses cryptographic weaknesses related to authentication failures and improper implementation of authentication mechanisms. This flaw creates an environment where the confidentiality of encrypted data can be compromised through tampering attacks, as the system cannot distinguish between legitimate and malicious modifications to the encrypted content.
The operational impact of this vulnerability is substantial and far-reaching across systems utilizing the affected Perl module. Any application relying on the CryptX module for authenticated encryption operations becomes susceptible to padding oracle attacks, ciphertext modification attacks, and other forms of cryptographic tampering. The vulnerability affects systems where data integrity is paramount, including secure communications, database encryption, and any scenario where authenticated encryption is employed to ensure that data has not been altered. Attackers could exploit this weakness by crafting modified ciphertext that would decrypt successfully without triggering any verification errors, potentially allowing them to inject malicious content or manipulate encrypted data streams. The implications extend beyond simple data corruption, as this vulnerability fundamentally compromises the security model of the encryption system, making it vulnerable to active attacks that would otherwise be prevented by proper authentication tag verification. This weakness particularly impacts environments where the confidentiality and integrity of data are critical requirements, such as financial transactions, healthcare records, and secure messaging systems.
Mitigation strategies for CVE-2018-25099 involve immediate upgrading to CryptX version 0.062 or later, which contains the necessary patches to restore proper authentication tag verification in the affected functions. System administrators should conduct comprehensive audits of all applications that utilize the CryptX module to identify potential exposure and ensure that all instances are updated to secure versions. Additionally, organizations should implement monitoring and logging mechanisms to detect any unusual decryption activities that might indicate exploitation attempts. The vulnerability highlights the importance of proper cryptographic implementation and the critical need for thorough testing of authentication mechanisms within cryptographic libraries. Security teams should also consider implementing additional layers of protection such as integrity checking at higher protocol levels or application-specific validation mechanisms to provide defense-in-depth against potential exploitation. The remediation process should include thorough regression testing to ensure that the updated module does not introduce compatibility issues with existing applications while maintaining the necessary security enhancements. Organizations should also review their cryptographic implementation practices to prevent similar vulnerabilities in other components of their security infrastructure.