CVE-2018-18021 Explained : Impact and Mitigation

A security vulnerability in the Linux kernel version prior to 4.18.12 on the arm64 platform allows attackers to exploit the KVM_SET_ON_REG ioctl in the arch/arm64/kvm/guest.c module, potentially leading to a denial of service or full control over the hypervisor's registers.

Understanding CVE-2018-18021

This CVE involves a mishandling of the KVM_SET_ON_REG ioctl in the Linux kernel, impacting the arm64 platform.

What is CVE-2018-18021?

The vulnerability allows attackers with the ability to create virtual machines to redirect the hypervisor's control flow, gaining full control over the registers and potentially causing a denial of service through a hypervisor panic.

The Impact of CVE-2018-18021

Attackers can exploit the vulnerability to redirect the hypervisor's control flow, granting them full control over the registers.
An attacker can trigger a denial of service by causing a hypervisor panic through an illegal exception return.
The vulnerability arises due to insufficient restrictions on userspace access to the core register file and inadequate validation of PSTATE.M.

Technical Details of CVE-2018-18021

The technical aspects of the CVE.

Vulnerability Description

The vulnerability is due to the mishandling of the KVM_SET_ON_REG ioctl in the arch/arm64/kvm/guest.c module.

Affected Systems and Versions

Linux kernel versions prior to 4.18.12 on the arm64 platform are affected.

Exploitation Mechanism

Attackers with the ability to create virtual machines can exploit the vulnerability to redirect the hypervisor's control flow.

Mitigation and Prevention

Steps to mitigate and prevent exploitation of CVE-2018-18021.

Immediate Steps to Take

Apply patches provided by the Linux kernel maintainers.
Monitor vendor advisories for updates and apply them promptly.

Long-Term Security Practices

Regularly update and patch the Linux kernel to the latest stable version.
Implement strong access controls and monitoring mechanisms to detect unauthorized activities.

Patching and Updates

Update the Linux kernel to version 4.18.12 or later to mitigate the vulnerability.