CVE-2021-35540 in VM VirtualBox
Summary
by MITRE • 10/20/2021
Vulnerability in the Oracle VM VirtualBox product of Oracle Virtualization (component: Core). The supported version that is affected is Prior to 6.1.28. Easily exploitable vulnerability allows low privileged attacker with logon to the infrastructure where Oracle VM VirtualBox executes to compromise Oracle VM VirtualBox. Successful attacks of this vulnerability can result in unauthorized ability to cause a hang or frequently repeatable crash (complete DOS) of Oracle VM VirtualBox. CVSS 3.1 Base Score 5.5 (Availability impacts). CVSS Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).
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Analysis
by VulDB Data Team • 10/27/2021
The vulnerability identified as CVE-2021-35540 represents a significant availability risk within Oracle VM VirtualBox virtualization platform, specifically affecting versions prior to 6.1.28. This weakness resides in the Core component of the virtualization software, which serves as the fundamental foundation for virtual machine operations and system management. The vulnerability operates at a low privilege level, requiring only local access to the host system where VirtualBox is executing, making it particularly concerning for environments where multiple users share the same physical infrastructure. The attack vector analysis reveals that an authenticated local user with logon credentials can exploit this flaw, suggesting that the vulnerability may be leveraged by insiders or compromised accounts with legitimate access to the system.
The technical flaw manifests as a memory corruption issue that leads to denial of service conditions within the VirtualBox core functionality. This type of vulnerability typically stems from inadequate input validation or improper memory management within the virtualization layer, allowing an attacker to craft specific inputs that cause the virtualization engine to crash or become unresponsive. The CVSS score of 5.5 indicates a medium severity impact with availability being the primary concern, though the vulnerability's exploitation requires local system access. This aligns with CWE-125, which describes out-of-bounds read vulnerabilities, and CWE-129, which covers insufficient input validation issues. The vulnerability's characteristics suggest it may involve buffer overflows or similar memory management flaws that are common in virtualization software due to the complex interactions between guest and host operating systems.
The operational impact of this vulnerability extends beyond simple service disruption, as it can cause complete system unavailability for the virtualization platform, affecting all virtual machines running on the compromised system. This complete denial of service scenario represents a critical concern for enterprise environments that rely heavily on virtualization for their computing infrastructure, potentially leading to significant business disruption. Organizations utilizing VirtualBox for development, testing, or production workloads may experience extended downtime while system administrators investigate and remediate the issue. The vulnerability's ability to cause frequently repeatable crashes suggests that once exploited, it may be difficult to recover from without proper system restarts or virtual machine reinitialization. This behavior aligns with ATT&CK technique T1499.001, which covers network denial of service attacks, though in this case the impact occurs at the system level rather than network level.
Mitigation strategies for CVE-2021-35540 primarily focus on immediate patching of affected VirtualBox installations to version 6.1.28 or later, which contains the necessary security fixes to address the core memory management issues. System administrators should prioritize updating their VirtualBox environments and verify that all virtual machines are running on patched versions before returning to production use. Additional protective measures include implementing strict access controls to prevent unauthorized local access to systems running VirtualBox, monitoring system logs for signs of exploitation attempts, and maintaining regular backups of virtual machine configurations to facilitate rapid recovery in case of successful attacks. Organizations should also consider implementing network segmentation to limit the potential impact of local privilege escalation attacks and ensure that VirtualBox installations are properly hardened through configuration management practices. The vulnerability's classification as easily exploitable underscores the importance of rapid remediation and the need for organizations to maintain current patch management processes for critical virtualization infrastructure components.