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CVE-2019-20175 : What You Need to Know

Discover the impact of CVE-2019-20175, a vulnerability in QEMU versions 2.4.0 through 4.2.0. Learn about the exploitation mechanism and mitigation steps to secure your systems.

A vulnerability was found in the function ide_dma_cb() in the file hw/ide/core.c in QEMU versions 2.4.0 through 4.2.0. Exploiting this vulnerability, the guest system can cause a crash in the host system's QEMU process by using a specific SCSI_IOCTL_SEND_COMMAND. This particular exploit triggers an assertion, suggesting that the size of successful DMA transfers must be a multiple of 512, which is the size of a sector. It should be noted that a member of the QEMU security team disputes the significance of this issue, as a privileged guest user has various methods to cause a similar denial-of-service effect without triggering the mentioned assertion.

Understanding CVE-2019-20175

This section provides insights into the nature and impact of the CVE-2019-20175 vulnerability.

What is CVE-2019-20175?

CVE-2019-20175 is a vulnerability in the function ide_dma_cb() in QEMU versions 2.4.0 through 4.2.0. It allows a guest system to crash the host system's QEMU process by exploiting a specific SCSI_IOCTL_SEND_COMMAND.

The Impact of CVE-2019-20175

The vulnerability can lead to a denial-of-service effect by causing a crash in the host system's QEMU process. Despite the assertion triggered, a privileged guest user can achieve a similar effect through alternative methods.

Technical Details of CVE-2019-20175

This section delves into the technical aspects of CVE-2019-20175.

Vulnerability Description

The vulnerability resides in the function ide_dma_cb() in the file hw/ide/core.c in QEMU versions 2.4.0 through 4.2.0. It allows a guest system to crash the host system's QEMU process using a specific SCSI_IOCTL_SEND_COMMAND.

Affected Systems and Versions

        Systems running QEMU versions 2.4.0 through 4.2.0 are vulnerable to this exploit.

Exploitation Mechanism

        The vulnerability can be exploited by the guest system using a specific SCSI_IOCTL_SEND_COMMAND to trigger an assertion related to the size of successful DMA transfers.

Mitigation and Prevention

This section outlines steps to mitigate and prevent the CVE-2019-20175 vulnerability.

Immediate Steps to Take

        Update QEMU to a version beyond 4.2.0 to eliminate the vulnerability.
        Monitor and restrict guest system activities to prevent unauthorized exploitation.

Long-Term Security Practices

        Implement regular security audits and assessments to identify and address vulnerabilities promptly.
        Educate users on secure practices to minimize the risk of exploitation.

Patching and Updates

        Stay informed about security updates and patches released by QEMU to address known vulnerabilities.

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