CVE-2023-0751 in FreeBSD
Summary
by MITRE • 02/08/2023
When GELI reads a key file from standard input, it does not reuse the key file to initialize multiple providers at once resulting in the second and subsequent devices silently using a NULL key as the user key file. If a user only uses a key file without a user passphrase, the master key is encrypted with an empty key file allowing trivial recovery of the master key.
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Analysis
by VulDB Data Team • 03/09/2023
The vulnerability identified as CVE-2023-0751 affects the GELI (GEOM Enhanced LUKS Interface) encryption framework used in FreeBSD systems. This flaw represents a critical weakness in the cryptographic key management process that can lead to complete bypass of disk encryption protections. The issue manifests when GELI processes key files provided via standard input, specifically failing to properly handle key material reuse across multiple encryption providers. The root cause stems from improper key initialization logic that does not maintain the integrity of the key file data when multiple devices are being configured simultaneously. This design flaw creates a scenario where subsequent devices in a multi-device setup silently default to using NULL key material instead of the intended user-provided key file.
The technical implications of this vulnerability are severe as it directly impacts the cryptographic security model of the encryption system. When users provide key files for GELI encryption without also specifying passphrases, the system encrypts the master key using an empty key file, effectively creating a trivial recovery path for attackers. This behavior violates fundamental security principles outlined in the Common Weakness Enumeration catalog under CWE-310, which addresses cryptographic weaknesses related to key management and entropy sources. The vulnerability essentially creates a backdoor scenario where the encryption becomes ineffective against determined attackers who can exploit the NULL key usage pattern. According to MITRE ATT&CK framework, this weakness maps to T1552.004 - Unsecured Credentials, as it involves the improper handling of cryptographic keys that can be trivially recovered.
The operational impact of CVE-2023-0751 extends beyond simple data exposure to compromise the entire security posture of systems relying on GELI encryption. Organizations using FreeBSD systems with GELI-based disk encryption are at risk of having their encrypted data trivially accessible to attackers who can exploit this flaw to recover master keys without any authentication. The vulnerability affects systems where users rely solely on key files for encryption without additional passphrase protection, creating a false sense of security. The silent failure mode makes this particularly dangerous as administrators may not immediately detect that encryption is compromised, leading to potential data breaches and compliance violations. Systems with multiple encrypted devices using the same key file are especially vulnerable since the flaw affects all subsequent devices after the first one, creating cascading security failures. The weakness represents a critical failure in the principle of least privilege and proper cryptographic key handling, as defined in industry security standards and best practices for enterprise encryption implementations.