CVE-2020-8876 in Parallels Desktop
Summary
by MITRE
This vulnerability allows local attackers to disclose information on affected installations of Parallels Desktop 15.1.2-47123. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability. The specific flaw exists within the IOCTL handler. The issue results from the lack of proper validation of user-supplied data, which can result in a read past the end of an allocated buffer. An attacker can leverage this in conjunction with other vulnerabilities to execute arbitrary code in the context of the kernel. Was ZDI-CAN-10029.
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Analysis
by VulDB Data Team • 05/11/2024
CVE-2020-8876 represents a critical information disclosure vulnerability affecting Parallels Desktop version 15.1.2-47123 and potentially other variants within the 15.x series. This vulnerability resides within the kernel-mode driver component of the virtualization platform, specifically within the IOCTL (Input/Output Control) handler mechanism that facilitates communication between user-space applications and kernel-space drivers. The flaw stems from inadequate input validation procedures where the driver fails to properly sanitize user-supplied data before processing it within kernel memory contexts. This absence of proper boundary checking creates a classic buffer overread condition that can be exploited by malicious actors who have already achieved low-privileged code execution on the target system. The vulnerability manifests when the IOCTL handler processes malformed input data, causing the driver to read memory beyond the allocated buffer boundaries, thereby exposing sensitive kernel memory contents to unauthorized access.
The technical exploitation of this vulnerability follows a well-established pattern that aligns with CWE-125: "Out-of-bounds Read" and represents a direct violation of secure coding practices for kernel-mode drivers. When an attacker successfully crafts malicious input parameters and submits them through the IOCTL interface, the kernel driver's insufficient validation allows the read operation to extend beyond the intended buffer limits. This buffer overread can potentially expose kernel memory structures, sensitive data, or even cryptographic keys that may be stored in adjacent memory regions. The vulnerability's classification as a local privilege escalation vector becomes apparent when considering that an attacker with low-privileged access can leverage this information disclosure to gather intelligence about the kernel memory layout and potentially identify additional exploitable conditions. The attack chain typically begins with a successful low-privileged code execution primitive, followed by the exploitation of this buffer overread vulnerability to extract kernel memory contents, which can then be used to facilitate more sophisticated attacks such as kernel code execution or privilege escalation.
From an operational impact perspective, this vulnerability poses significant risks to organizations utilizing Parallels Desktop for virtualization environments, particularly in enterprise settings where multiple users may have access to the system. The information disclosure aspect can reveal sensitive kernel memory contents that might include system configuration details, memory addresses, or other data that could aid in crafting more advanced attacks. The vulnerability's potential to enable kernel code execution represents a severe escalation risk that could allow attackers to gain complete system control, bypass security controls, and establish persistent access. The fact that this vulnerability was tracked as ZDI-CAN-10029 indicates it was recognized by the security community and addressed through coordinated vulnerability disclosure channels, highlighting the severity and potential widespread impact across various deployment scenarios. Organizations running affected versions of Parallels Desktop face the risk of unauthorized access to virtual machine environments, potential data breaches, and complete system compromise if this vulnerability remains unpatched.
The remediation approach for CVE-2020-8876 requires immediate application of the vendor-provided security patch that addresses the buffer overread condition in the IOCTL handler implementation. System administrators should prioritize patch management activities to ensure all affected Parallels Desktop installations are updated to versions that contain proper input validation and boundary checking mechanisms. Additionally, organizations should implement monitoring and logging controls to detect anomalous IOCTL activity that might indicate exploitation attempts. Security controls should include kernel-mode driver integrity checking, runtime protection mechanisms, and network segmentation to limit the potential impact of successful exploitation. The vulnerability demonstrates the critical importance of secure driver development practices and proper input validation in kernel-space components, as outlined in the ATT&CK framework's kernel-mode driver manipulation techniques. Organizations should also consider implementing additional security controls such as application whitelisting, kernel patch protection, and regular security assessments of virtualization environments to prevent similar vulnerabilities from being exploited in the future.