CVE-2017-17741 in Linux
Summary
by MITRE
The KVM implementation in the Linux kernel through 4.14.7 allows attackers to cause a denial of service (write_mmio stack-based out-of-bounds read) or possibly have unspecified other impact, related to arch/x86/kvm/x86.c and include/trace/events/kvm.h.
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Analysis
by VulDB Data Team • 01/18/2023
The vulnerability CVE-2017-17741 represents a critical flaw in the Linux kernel's KVM (Kernel-based Virtual Machine) implementation that affects versions through 4.14.7. This issue resides within the x86 architecture's KVM subsystem and specifically involves improper handling of memory-mapped I/O operations during virtual machine execution. The vulnerability manifests as a stack-based out-of-bounds read condition that occurs when processing write_mmio operations, fundamentally compromising the integrity of the kernel's memory management during virtualization operations.
The technical exploitation of this vulnerability stems from inadequate bounds checking in the KVM implementation's handling of memory-mapped I/O writes. When a virtual machine attempts to write to memory-mapped I/O regions, the kernel's x86 KVM subsystem fails to properly validate the memory access boundaries before performing the operation. This flaw exists in the arch/x86/kvm/x86.c source file where the write_mmio handler processes guest memory operations, and is further documented in include/trace/events/kvm.h which defines the tracing events for KVM operations. The insufficient validation allows attackers to craft malicious guest VM operations that trigger buffer over-read conditions on the kernel stack, potentially leading to information disclosure or system instability.
From an operational perspective, this vulnerability poses significant risks to virtualized environments where multiple tenants share the same physical hardware. An attacker with access to a guest virtual machine could leverage this flaw to cause denial of service conditions that crash the host kernel, effectively terminating all virtual machines running on that physical system. The impact extends beyond simple service disruption as the vulnerability may potentially allow for unspecified other impacts including privilege escalation or information leakage, making it particularly dangerous in multi-tenant cloud environments or enterprise virtualization deployments. The vulnerability affects all KVM implementations that utilize the affected kernel versions, regardless of the specific virtualization platform or hypervisor configuration.
The mitigation strategies for CVE-2017-17741 primarily involve upgrading to kernel versions 4.14.8 or later where the vulnerability has been patched. Organizations should prioritize patching their virtualization infrastructure to prevent exploitation, particularly in environments where guest VMs might be compromised or untrusted. Additionally, implementing proper access controls and monitoring for unusual KVM operations can help detect potential exploitation attempts. This vulnerability aligns with CWE-129, which addresses improper validation of array indices, and maps to ATT&CK technique T1059.001 for execution through guest operating systems. System administrators should also consider implementing network segmentation and virtual machine isolation measures to limit the potential impact of successful exploitation attempts, while maintaining comprehensive logging of KVM operations for forensic analysis purposes.