CVE-2018-3665 in macOS
Summary
by MITRE
System software utilizing Lazy FP state restore technique on systems using Intel Core-based microprocessors may potentially allow a local process to infer data from another process through a speculative execution side channel.
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Analysis
by VulDB Data Team • 04/05/2023
This vulnerability represents a sophisticated speculative execution side channel attack that exploits the lazy floating point state restoration mechanism implemented in Intel Core-based processors. The flaw specifically affects systems where the processor's microarchitecture employs lazy floating point state management, a technique designed to optimize performance by deferring the saving and restoring of floating point registers until absolutely necessary. When a process switches context, the processor may not immediately save the floating point state of the previous process, instead relying on speculative execution to handle state transitions. This design optimization creates a potential information leakage channel that adversaries can exploit to infer sensitive data from other processes running on the same system.
The technical implementation of this vulnerability stems from the interaction between the processor's speculative execution engine and the lazy floating point state restoration mechanism. During normal operation, when a process is preempted and another process begins execution, the processor may defer the actual saving of floating point register contents. However, if the processor's speculative execution engine continues to access floating point registers during the transition period, it can potentially observe the contents of registers that were not yet properly saved. This creates a scenario where a malicious process can monitor timing variations or other observable side effects to reconstruct data that should be isolated between processes. The vulnerability is particularly concerning because it operates at the microarchitectural level and can be exploited without requiring elevated privileges or direct access to the target process's memory space.
The operational impact of CVE-2018-3665 extends beyond simple information disclosure, as it represents a fundamental flaw in how modern processors handle state transitions during concurrent execution. Attackers can leverage this vulnerability to perform cache timing attacks or other side channel techniques to extract sensitive information such as cryptographic keys, passwords, or other confidential data from neighboring processes. This vulnerability affects a wide range of systems including servers, desktop computers, and mobile devices that utilize Intel Core processors, making it particularly dangerous in multi-tenant environments where multiple processes or users share the same hardware. The attack vector is particularly insidious because it requires no special permissions or access rights, relying instead on the inherent design of the processor's microarchitecture to create the information leakage channel.
Mitigation strategies for this vulnerability typically involve implementing software-level protections that either disable or modify the problematic lazy state restoration behavior, though these approaches often come with performance penalties. The most effective long-term solutions involve updating microcode firmware to address the underlying architectural flaw, as well as implementing operating system-level protections such as kernel page table isolation or other memory protection mechanisms. Organizations should also consider deploying additional monitoring and detection capabilities to identify potential exploitation attempts, as the vulnerability operates at a level that is difficult to detect through conventional security measures. This vulnerability aligns with the broader category of speculative execution side channel attacks that have been documented under CWE-124 and is closely related to the ATT&CK technique T1059.001, which covers process injection and context switching attacks that exploit processor microarchitectural weaknesses to gain unauthorized access to sensitive information through indirect means.