CVE-2018-5407 in CPU
Summary
by MITRE
Simultaneous Multi-threading (SMT) in processors can enable local users to exploit software vulnerable to timing attacks via a side-channel timing attack on 'port contention'.
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Analysis
by VulDB Data Team • 07/30/2024
The vulnerability identified as CVE-2018-5407 represents a significant side-channel security weakness inherent in modern processor architectures that implement Simultaneous Multi-threading technology. This flaw exploits the fundamental design of SMT processors where multiple execution threads share the same physical processor core, creating opportunities for malicious code to infer sensitive information through timing variations. The vulnerability specifically targets software applications that are susceptible to timing attacks, leveraging the inherent contention that occurs when multiple threads compete for shared execution resources within the same core.
The technical exploitation mechanism operates through port contention analysis, where malicious local users can monitor and measure the time variations in instruction execution to deduce information about the operations of other threads running on the same physical core. This occurs because SMT processors maintain shared execution units such as execution ports, cache levels, and memory subsystems that can create measurable timing differences when multiple threads access these resources simultaneously. The timing variations directly correlate to the underlying computational activities of competing threads, enabling attackers to perform sophisticated side-channel analysis that can reveal cryptographic keys, secret data, or other sensitive information.
The operational impact of this vulnerability extends beyond simple information disclosure, as it fundamentally undermines the security assumptions of multi-threaded applications running on affected processors. Local attackers with access to the system can potentially extract confidential data from other processes running on the same physical core, making this a particularly dangerous vulnerability for environments hosting multiple applications or users. The attack vector is particularly concerning because it requires minimal privileges and can be executed from within the same security context as the target processes, making detection and prevention challenging. This vulnerability affects a broad range of processor architectures including intel x86 processors and other implementations that support simultaneous multi-threading, creating widespread exposure across enterprise and cloud computing environments.
Mitigation strategies for CVE-2018-5407 typically involve disabling SMT functionality at the hardware level through BIOS/UEFI configuration options or operating system kernel parameters, though this approach incurs significant performance penalties. Alternative approaches include implementing software-based countermeasures such as constant-time algorithms, randomization techniques, and memory access pattern obfuscation to prevent timing-based information leakage. Organizations should also consider microcode updates provided by processor vendors, though these may not fully address the underlying architectural vulnerability. The mitigation approach should align with industry standards such as those recommended in the CWE-116 weakness classification for improper encoding or representation and ATT&CK technique T1059.001 for command and scripting interpreter to ensure comprehensive protection against this class of side-channel attacks.