CVE-2025-4382 in Red Hat
Summary
by MITRE • 05/09/2025
A flaw was found in systems utilizing LUKS-encrypted disks with GRUB configured for TPM-based auto-decryption. When GRUB is set to automatically decrypt disks using keys stored in the TPM, it reads the decryption key into system memory. If an attacker with physical access can corrupt the underlying filesystem superblock, GRUB will fail to locate a valid filesystem and enter rescue mode. At this point, the disk is already decrypted, and the decryption key remains loaded in system memory. This scenario may allow an attacker with physical access to access the unencrypted data without any further authentication, thereby compromising data confidentiality. Furthermore, the ability to force this state through filesystem corruption also presents a data integrity concern.
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Analysis
by VulDB Data Team • 07/29/2025
This vulnerability represents a critical security flaw in the LUKS disk encryption implementation when combined with GRUB's TPM-based auto-decryption feature. The issue stems from the fundamental design assumption that the encryption key remains secure only while the system is in normal operation, but fails to account for the persistence of decrypted key material in system memory even after the system enters recovery or rescue mode. The vulnerability manifests when an attacker with physical access can manipulate the filesystem superblock, causing GRUB to fail in locating a valid filesystem and subsequently entering rescue mode. This process, while intended as a recovery mechanism, inadvertently exposes a critical security gap where the decryption key remains resident in memory, creating an attack surface that bypasses traditional authentication mechanisms. The flaw directly impacts the confidentiality and integrity of data stored on LUKS-encrypted volumes, as demonstrated by the ability to access unencrypted data through the compromised memory state.
The technical implementation of this vulnerability involves multiple layers of the system architecture that interact in a dangerous manner. When GRUB is configured with TPM-based auto-decryption, it retrieves encryption keys from the TPM and loads them into system memory for the decryption process. The system design does not properly account for the scenario where a corrupted filesystem superblock forces GRUB into rescue mode while maintaining the key in memory. This creates a persistent memory state where the decryption key remains accessible to an attacker who can potentially access system memory through various means such as direct memory access or exploitation of other system vulnerabilities. The underlying architecture fails to implement proper memory sanitization or key invalidation procedures when transitioning from normal operation to rescue mode, violating fundamental security principles of key management and memory protection. This vulnerability aligns with CWE-256, which addresses the issue of insecure key storage, and CWE-284, which deals with improper access control mechanisms.
The operational impact of this vulnerability extends beyond simple data confidentiality breaches to encompass broader system security concerns. An attacker with physical access can exploit this flaw to gain unauthorized access to sensitive data without requiring additional authentication factors, effectively neutralizing the encryption protection that LUKS provides. The vulnerability is particularly concerning because it operates at the bootloader level, making it extremely difficult to detect and remediate through traditional operating system security measures. The ability to force the system into a compromised state through filesystem corruption also introduces data integrity risks, as the attacker can potentially manipulate the system's recovery process to achieve persistent access. This attack vector is particularly dangerous in environments where physical security controls are inadequate or where devices may be physically compromised, such as in enterprise environments with unsecured workstations or in scenarios involving lost or stolen devices.
Mitigation strategies for this vulnerability must address both the immediate security gap and the underlying architectural design flaws. The primary recommendation involves implementing proper memory sanitization procedures when GRUB enters rescue mode, ensuring that encryption keys are cleared from system memory before the system enters recovery state. Organizations should consider disabling automatic TPM-based decryption in environments where physical security cannot be guaranteed, or implementing additional authentication layers that require user interaction even during system recovery. The implementation of secure boot mechanisms and proper TPM configuration can help reduce the attack surface, while regular system audits should monitor for unauthorized filesystem modifications that could trigger this vulnerability. System administrators should also implement monitoring solutions that can detect unusual memory access patterns or attempts to access decrypted data during system recovery states. This vulnerability demonstrates the critical importance of considering attack vectors at all system levels, including bootloader and firmware components, and highlights the need for comprehensive security architectures that address the entire attack surface rather than focusing solely on traditional operating system security boundaries. The remediation approach should also consider implementing proper key lifecycle management and ensuring that system recovery mechanisms do not inadvertently expose cryptographic material, aligning with security best practices outlined in industry standards such as NIST SP 800-57 for key management and the MITRE ATT&CK framework's consideration of boot and firmware level attacks.