CVE-2014-3646 in Linux
Summary
by MITRE
arch/x86/kvm/vmx.c in the KVM subsystem in the Linux kernel through 3.17.2 does not have an exit handler for the INVVPID instruction, which allows guest OS users to cause a denial of service (guest OS crash) via a crafted application.
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Analysis
by VulDB Data Team • 02/23/2022
The vulnerability identified as CVE-2014-3646 resides within the Kernel-based Virtual Machine (KVM) subsystem of the Linux kernel version 3.17.2 and earlier. This issue specifically affects the Intel Virtualization Technology for Directed I/O (VT-d) implementation within the KVM hypervisor, where the virtual machine monitor fails to properly handle the INVVPID instruction. The INVVPID instruction is a critical component of Intel's virtualization architecture designed to invalidate virtual processor identifiers in the translation lookaside buffer, ensuring memory consistency across virtual machines. The flaw occurs in the vmx.c file which manages the virtual machine execution environment for Intel processors, creating a critical gap in the hypervisor's instruction handling capabilities.
The technical implementation flaw stems from the absence of a dedicated exit handler for the INVVPID instruction within the KVM subsystem's virtual machine execution framework. When a guest operating system attempts to execute this instruction, the hypervisor lacks the proper mechanism to intercept and process the instruction appropriately. This creates a scenario where the virtual machine execution environment cannot gracefully handle the instruction, leading to an immediate termination of the guest operating system. The vulnerability represents a classic case of incomplete virtualization support where the hypervisor fails to provide adequate handling for advanced virtualization instructions, resulting in a denial of service condition that crashes the entire guest environment.
The operational impact of this vulnerability extends beyond simple system crashes, as it fundamentally compromises the reliability and stability of virtualized environments. Attackers with access to guest operating systems can exploit this weakness to systematically crash virtual machines, potentially causing widespread service disruption in cloud computing environments, containerized applications, and virtual desktop infrastructures. The vulnerability affects any system running Linux kernel versions up to 3.17.2 that utilizes KVM for virtualization, making it particularly dangerous in production environments where virtualization is extensively deployed. The denial of service condition occurs without requiring elevated privileges, making it accessible to any user within the guest operating system, thereby creating a significant security risk for multi-tenant cloud environments.
Mitigation strategies for CVE-2014-3646 involve immediate kernel updates to versions 3.17.3 and later, which contain the necessary patches to implement proper INVVPID instruction handling. Organizations should also consider implementing additional monitoring and alerting mechanisms to detect unauthorized virtual machine crashes or unexpected system behavior that might indicate exploitation attempts. The vulnerability aligns with CWE-122, which describes improper restriction of operations within a recognized security boundary, and corresponds to ATT&CK technique T1499.004, which covers network denial of service attacks through hypervisor manipulation. System administrators should also review their virtualization configurations and ensure that guest operating systems are regularly updated to prevent exploitation of similar vulnerabilities in the virtualization stack, particularly focusing on maintaining up-to-date hypervisor implementations and monitoring for potential privilege escalation vectors that could leverage this flaw.