CVE-2017-5691 in Xeon-1200
Summary
by MITRE
Incorrect check in Intel processors from 6th and 7th Generation Intel Core Processor Families, Intel Xeon E3-1500M v5 and v6 Product Families, and Intel Xeon E3-1200 v5 and v6 Product Families allows compromised system firmware to impact SGX security via incorrect early system state.
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Analysis
by VulDB Data Team • 11/01/2019
The vulnerability identified as CVE-2017-5691 represents a critical flaw in Intel processors spanning the 6th and 7th generation Core processor families along with specific Xeon E3 product lines. This vulnerability specifically targets the Secure Guard Extensions (SGX) security feature that Intel developed to provide hardware-based memory encryption and protection for sensitive application data. The flaw manifests in an incorrect check mechanism within the processor's early system state initialization, which creates a potential pathway for malicious firmware to undermine the fundamental security guarantees that SGX is designed to provide.
The technical root cause of this vulnerability lies in the improper validation of system state during the processor's boot sequence and early initialization phases. When system firmware becomes compromised, the flawed check mechanism fails to properly verify the integrity of the early system environment, allowing malicious actors to potentially manipulate or bypass the security boundaries that SGX establishes. This issue creates a dangerous scenario where even if the firmware itself is compromised, the processor's security features may not function as intended, effectively rendering the SGX protections ineffective against sophisticated attacks that target the system's early boot stages.
The operational impact of CVE-2017-5691 is particularly severe given that SGX is designed to protect sensitive data and cryptographic operations from even hypervisor-level attacks and privileged software. When this vulnerability is exploited, it essentially undermines the core premise of SGX security, allowing attackers with compromised firmware access to potentially bypass memory encryption protections and gain access to data that was previously considered isolated and protected. This vulnerability particularly affects systems where firmware integrity cannot be guaranteed, as the compromised firmware can manipulate the early system state to disable or subvert the SGX security features.
From a cybersecurity perspective, this vulnerability aligns with CWE-284, which addresses improper access control, and represents a significant weakness in the processor's security architecture that violates the principle of least privilege. The ATT&CK framework categorizes this issue under privilege escalation and defense evasion techniques, as attackers can leverage this vulnerability to bypass hardware-level protections. Organizations running systems with affected processors face increased risk of data breaches, especially those handling sensitive information where SGX was previously relied upon for protection. The vulnerability particularly impacts enterprise environments and cloud service providers where SGX is used to protect confidential computing workloads, making it a critical concern for any system where data isolation and memory protection are paramount.
Mitigation strategies for CVE-2017-5691 primarily involve firmware updates from Intel and system administrators must ensure that all affected processors receive the appropriate microcode updates. Additionally, organizations should implement robust firmware integrity monitoring solutions and consider architectural redesigns that reduce reliance on potentially compromised firmware components. The vulnerability highlights the critical importance of maintaining secure boot chains and proper firmware validation processes, as it demonstrates how flaws in early system initialization can undermine even the most sophisticated hardware security features.