CVE-2019-5525 in Workstation
Summary
by MITRE
VMware Workstation (15.x before 15.1.0) contains a use-after-free vulnerability in the Advanced Linux Sound Architecture (ALSA) backend. A malicious user with normal user privileges on the guest machine may exploit this issue in conjunction with other issues to execute code on the Linux host where Workstation is installed.
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Analysis
by VulDB Data Team • 09/28/2023
The vulnerability identified as CVE-2019-5525 represents a critical use-after-free flaw within VMware Workstation's Advanced Linux Sound Architecture ALSA backend implementation. This vulnerability affects VMware Workstation versions 15.x prior to 15.1.0 and demonstrates how virtualization software can introduce security risks that extend beyond the guest operating system boundaries. The flaw specifically manifests in the handling of audio subsystem components within the virtualized environment, creating a potential attack vector that could allow privilege escalation and remote code execution on the host system.
The technical nature of this vulnerability stems from improper memory management within the ALSA backend driver that VMware implements for guest operating systems. When a guest Linux system interacts with audio devices through VMware's virtualized audio infrastructure, the system fails to properly validate memory references after objects have been freed, creating a use-after-free condition. This type of vulnerability falls under CWE-416, which specifically addresses the use of freed memory, and represents a classic example of how improper resource management can lead to arbitrary code execution. The vulnerability occurs during the processing of audio data streams that traverse the virtualized audio interface, where the virtualization layer does not adequately protect against malicious input that could trigger the freed memory access pattern.
The operational impact of this vulnerability extends beyond simple guest-to-host information disclosure, as it enables a malicious user with normal privileges within the guest environment to potentially execute arbitrary code on the underlying host system. This represents a significant escalation of privileges that violates the fundamental security boundary that virtualization platforms are designed to maintain. The attack requires a malicious user to be present within the guest operating system, but once exploited, the vulnerability allows for code execution with the privileges of the host system process running VMware Workstation. This type of attack vector aligns with ATT&CK technique T1059, which covers command and scripting interpreter usage, and T1068, which addresses exploit for privilege escalation, as the vulnerability enables an attacker to leverage guest privileges to gain host-level access.
The exploitation of this vulnerability typically requires a multi-stage attack approach where the malicious user first establishes a foothold within the guest system, then leverages the use-after-free condition through carefully crafted audio operations or data streams. The attack may involve manipulating audio device drivers or creating specific audio processing scenarios that trigger the memory corruption. This vulnerability demonstrates how virtualization environments can become attack surfaces where guest operating system compromises can lead to host system exploitation, highlighting the importance of maintaining strict isolation boundaries between virtualized environments and host systems. Organizations using VMware Workstation should prioritize patching to version 15.1.0 or later, as this update addresses the memory management issues within the ALSA backend and prevents the use-after-free condition from being exploited.
Security practitioners should consider implementing additional monitoring and detection measures around audio subsystem interactions within virtualized environments, as these vulnerabilities often remain undetected by traditional security controls. The vulnerability also underscores the importance of regular security assessments of virtualization platforms and their associated components, as third-party drivers and backend services can introduce unexpected security risks. This particular vulnerability serves as a reminder that virtualization security is not just about protecting guest systems from external threats, but also about maintaining the integrity of the virtualization layer itself to prevent guest-to-host privilege escalation attacks.