CVE-2016-6225 in XtraBackup
Summary
by MITRE
xbcrypt in Percona XtraBackup before 2.3.6 and 2.4.x before 2.4.5 does not properly set the initialization vector (IV) for encryption, which makes it easier for context-dependent attackers to obtain sensitive information from encrypted backup files via a Chosen-Plaintext attack. NOTE: this vulnerability exists because of an incomplete fix for CVE-2013-6394.
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Analysis
by VulDB Data Team • 09/25/2024
The vulnerability identified as CVE-2016-6225 affects Percona XtraBackup versions prior to 2.3.6 and 2.4.x versions before 2.4.5, specifically within the xbcrypt encryption component. This flaw represents a critical weakness in the cryptographic implementation that undermines the confidentiality guarantees of encrypted backup files. The vulnerability stems from an incomplete remediation of a previous issue documented as CVE-2013-6394, demonstrating how remediation efforts can sometimes introduce new attack vectors when not thoroughly validated. The core problem manifests in the improper initialization vector (IV) handling during the encryption process, which fundamentally compromises the security properties of the encryption algorithm.
The technical flaw lies in the deterministic nature of IV usage within the encryption process, where the same IV is potentially reused for multiple encryption operations. This weakness enables attackers to perform chosen-plaintext attacks by strategically selecting plaintext inputs and analyzing the resulting ciphertext patterns. When the IV is not properly randomized for each encryption operation, it creates predictable relationships between plaintext and ciphertext blocks that can be exploited to recover sensitive information. The vulnerability operates at the cryptographic implementation level, specifically violating the fundamental principle that initialization vectors must be unique and unpredictable for each encryption operation to maintain semantic security.
From an operational perspective, this vulnerability poses significant risks to organizations relying on Percona XtraBackup for database encryption. Attackers with context-dependent access to encrypted backup files can potentially reconstruct sensitive data without requiring the encryption key, effectively bypassing the encryption protection mechanism. The impact extends beyond simple data exposure, as it undermines the integrity of the entire backup and recovery process, potentially exposing database credentials, user information, and other confidential data stored within the encrypted backups. This vulnerability particularly affects environments where backup files might be stored on compromised systems or accessed by unauthorized parties.
Security practitioners should implement immediate mitigations including upgrading to Percona XtraBackup versions 2.3.6 or 2.4.5 and later, which contain the proper IV handling implementation. Organizations should also conduct comprehensive assessments of their existing backup files to identify potential exposure windows and consider re-encrypting sensitive backup data using properly configured encryption parameters. The vulnerability aligns with CWE-327, which addresses the use of insecure cryptographic algorithms and improper implementation of cryptographic functions, and maps to ATT&CK technique T1552.001 for unsecured credentials and T1021.002 for remote services. Organizations should also consider implementing additional monitoring and access controls around backup storage systems to detect potential unauthorized access attempts that could exploit this vulnerability.