CVE-2016-6224 in eCryptfs
Summary
by MITRE
ecryptfs-setup-swap in eCryptfs does not prevent the unencrypted swap partition from activating during boot when using GPT partitioning on a (1) NVMe or (2) MMC drive, which allows local users to obtain sensitive information via unspecified vectors. NOTE: this vulnerability exists because of an incomplete fix for CVE-2015-8946.
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Analysis
by VulDB Data Team • 09/09/2022
The vulnerability described in CVE-2016-6224 affects the eCryptfs filesystem encryption implementation on Linux systems, specifically targeting the ecryptfs-setup-swap utility that manages swap partition activation during system boot. This security flaw represents a critical weakness in the encryption stack's handling of certain storage devices, particularly those utilizing Non-Volatile Memory Express (NVMe) or MultiMediaCard (MMC) interfaces with GUID Partition Table (GPT) formatting. The issue stems from an incomplete remediation of a previously identified vulnerability CVE-2015-8946, creating a persistent security gap that allows unauthorized access to sensitive data through mechanisms that are not explicitly detailed in the vulnerability description.
The technical flaw manifests when the system attempts to initialize swap partitions during the boot process on NVMe or MMC drives formatted with GPT partition tables. Under normal circumstances, eCryptfs should ensure that unencrypted swap partitions remain inactive until the system has completed its encryption setup and that sensitive data is properly protected. However, the flawed implementation fails to properly prevent the activation of these unencrypted swap partitions, creating a window of vulnerability where plaintext data from encrypted volumes could potentially be written to swap space. This behavior violates fundamental security principles of data protection and creates an attack surface that local users can exploit to gain access to information that should remain encrypted and protected.
The operational impact of this vulnerability extends beyond simple information disclosure, as it represents a fundamental breach in the trust model of encrypted storage systems. When local users can access data that should remain encrypted, it compromises the entire security posture of systems relying on eCryptfs for data protection. The vulnerability is particularly concerning because it affects the boot process, meaning that even systems that properly implement encryption at rest may become vulnerable during the critical initialization phase. This creates a scenario where sensitive information could be exposed through swap space, potentially including cryptographic keys, user credentials, or other confidential data that was intended to remain protected by the encryption mechanism. The vulnerability's persistence across different storage technologies and partitioning schemes makes it particularly dangerous as it affects a broad range of systems that utilize modern storage interfaces.
The security implications of this vulnerability align with several elements of the Common Weakness Enumeration framework, particularly CWE-200, which addresses "Information Exposure," and CWE-310, which covers "Cryptographic Issues." Additionally, this vulnerability maps to techniques described in the MITRE ATT&CK framework under T1003, "OS Credential Dumping," and T1005, "Data from Local System," as it enables unauthorized access to sensitive information that would typically be protected by encryption. The incomplete fix for CVE-2015-8946 suggests a pattern of remediation gaps that could indicate broader issues in how the eCryptfs project handles security patches and vulnerability management. Organizations should implement immediate mitigations including updating to patched versions of eCryptfs, disabling swap encryption if not required, or implementing additional monitoring to detect unauthorized access attempts to swap space during boot processes.
The remediation approach for this vulnerability requires careful consideration of system architecture and operational requirements. System administrators should prioritize applying the appropriate security patches that address the root cause of the incomplete fix, ensuring that swap partition activation is properly managed during system boot on affected storage devices. Additional protective measures may include implementing more restrictive swap space configurations, utilizing encrypted swap partitions, or employing alternative storage solutions that do not exhibit this vulnerability. Organizations should also consider implementing monitoring solutions to detect unauthorized access patterns to swap space and establish proper incident response procedures to address potential data exposure events. The vulnerability's nature as a boot-time issue necessitates comprehensive testing of system configurations to ensure that the fix properly addresses all affected storage interfaces and partitioning schemes, particularly those utilizing modern NVMe and MMC technologies that are increasingly common in enterprise and consumer environments.