CVE-2016-7798 in openssl gem
Summary
by MITRE
The openssl gem for Ruby uses the same initialization vector (IV) in GCM Mode (aes-*-gcm) when the IV is set before the key, which makes it easier for context-dependent attackers to bypass the encryption protection mechanism.
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Analysis
by VulDB Data Team • 11/11/2022
The vulnerability identified as CVE-2016-7798 affects the openssl gem in Ruby applications that utilize Galois/Counter Mode (GCM) encryption with AES algorithms. This issue stems from a critical flaw in how the gem handles initialization vectors during the encryption process, specifically when the IV is set prior to the key. The vulnerability operates at the intersection of cryptographic implementation security and software development practices, creating a significant risk for applications relying on secure encryption. The flaw represents a deviation from established cryptographic best practices where each encryption operation should utilize a unique and unpredictable initialization vector to maintain the security guarantees of authenticated encryption modes.
The technical root cause of this vulnerability lies in the improper handling of the IV generation sequence within the openssl gem's GCM implementation. When developers set the IV before establishing the encryption key, the gem fails to generate a fresh IV for each encryption operation, instead reusing a predetermined or predictable IV value. This behavior fundamentally undermines the security properties that GCM mode is designed to provide, as the reuse of IVs in GCM mode can lead to catastrophic security failures. The vulnerability is classified under CWE-329 which specifically addresses the use of predictable initialization vectors in cryptographic operations, making it a direct violation of established cryptographic security principles. The flaw operates at the application layer but has profound implications for the underlying cryptographic security mechanisms.
The operational impact of CVE-2016-7798 extends beyond simple data confidentiality breaches, as it enables context-dependent attackers to bypass encryption protection mechanisms entirely. Attackers can exploit this vulnerability to recover plaintext data or manipulate encrypted content without proper authorization, potentially leading to complete system compromise. The vulnerability is particularly dangerous in environments where sensitive data is processed using the affected openssl gem, as it provides attackers with a pathway to decrypt information that should remain protected. This weakness aligns with ATT&CK technique T1552.004 which covers unsecured credentials and T1074.001 which addresses data staging through the use of encrypted channels. The security implications are severe because GCM mode is commonly used in web applications, database encryption, and secure communication protocols where the integrity and confidentiality of data are paramount.
Mitigation strategies for this vulnerability require immediate action to update the openssl gem to versions that properly handle IV generation in GCM mode. Organizations should implement comprehensive patch management procedures to ensure all affected systems are updated promptly. Additionally, developers should review their code implementations to avoid setting IVs before keys in cryptographic operations, and should implement proper IV generation using cryptographically secure random number generators. The remediation process should include thorough testing of encryption operations to verify that each encryption uses a unique IV. Security teams should monitor their systems for potential exploitation attempts and implement network detection measures to identify suspicious activities that might indicate exploitation of this vulnerability. The fix addresses the fundamental issue described in CWE-329 by ensuring that initialization vectors are properly randomized and unique for each encryption operation, thereby restoring the security guarantees of the GCM mode implementation.