CVE-2018-1108 in Linux
Summary
by MITRE
kernel drivers before version 4.17-rc1 are vulnerable to a weakness in the Linux kernel's implementation of random seed data. Programs, early in the boot sequence, could use the data allocated for the seed before it was sufficiently generated.
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Analysis
by VulDB Data Team • 09/14/2025
The vulnerability identified as CVE-2018-1108 represents a critical weakness in the Linux kernel's random number generation mechanism that affected kernel versions prior to 4.17-rc1. This flaw specifically targeted the initialization phase of the kernel's random seed data implementation, creating a window of opportunity for adversaries to predict or manipulate the entropy sources that should have been unavailable during early boot processes. The vulnerability stems from inadequate synchronization between the random number generator's initialization and the availability of seed data, allowing programs executing during the boot sequence to access uninitialized or insufficiently randomized data.
The technical implementation of this vulnerability resides in the kernel's handling of random seed data during the early boot phase, where the random number generator subsystem fails to properly enforce access controls on entropy pools before they have been adequately seeded. This weakness falls under the category of improper initialization as classified by CWE-254, specifically CWE-254, which addresses security weaknesses related to improper initialization of security-critical resources. The flaw occurs because the kernel's random number generator does not maintain proper state transitions between uninitialized, partially initialized, and fully initialized phases of entropy collection, creating a race condition where programs can access potentially predictable seed data before the system has accumulated sufficient entropy.
During the operational impact, this vulnerability could enable attackers to compromise the randomness of cryptographic operations that depend on kernel-provided entropy, potentially affecting the security of encryption keys, session identifiers, and other security-sensitive values generated during the boot process. The attack surface extends to any application or kernel module that relies on the system's random number generator for security purposes during early boot phases, including but not limited to cryptographic key generation, secure boot processes, and network protocol implementations that require unpredictable values. This vulnerability directly impacts the fundamental security guarantees of the Linux kernel's cryptographic subsystem and could be leveraged to weaken the security of various security protocols that depend on unpredictable randomness.
The mitigation strategy for CVE-2018-1108 requires upgrading to kernel version 4.17-rc1 or later, where the random number generator's initialization sequence has been properly synchronized to prevent access to insufficiently seeded entropy pools. System administrators should prioritize kernel updates, particularly in environments where the boot process may be exploited by adversaries, and implement proper entropy monitoring to detect potential exploitation attempts. This vulnerability also highlights the importance of proper entropy management in kernel security implementations and aligns with ATT&CK technique T1496, which involves the manipulation of system resources to achieve persistence or privilege escalation. Organizations should also consider implementing entropy source monitoring and validation procedures to detect potential exploitation attempts and maintain compliance with security standards such as those outlined in the NIST SP 800-90A recommendation for random number generation.