CVE-2017-4934 in Workstation
Summary
by MITRE
VMware Workstation (12.x before 12.5.8) and Fusion (8.x before 8.5.9) contain a heap buffer-overflow vulnerability in VMNAT device. This issue may allow a guest to execute code on the host.
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Analysis
by VulDB Data Team • 01/24/2021
The vulnerability identified as CVE-2017-4934 represents a critical heap buffer-overflow flaw affecting VMware Workstation versions 12.x prior to 12.5.8 and VMware Fusion versions 8.x prior to 8.5.9. This vulnerability specifically resides within the VMNAT (Virtual Machine NAT) device component that facilitates network communication between virtual machines and host systems. The flaw arises from insufficient input validation and memory management within the NAT implementation, creating a condition where malicious input can overwrite adjacent memory locations in the heap. This type of vulnerability falls under CWE-121, heap-based buffer overflow, which is classified as a fundamental memory safety issue that can lead to arbitrary code execution.
The technical exploitation of this vulnerability occurs when a malicious guest operating system attempts to send specially crafted network packets through the VMNAT device. The insufficient bounds checking in the NAT device processing code allows an attacker to overflow a heap buffer and potentially overwrite critical memory regions including function pointers, return addresses, or other control data structures. When the vulnerable code executes with the corrupted heap memory, it can redirect program execution flow to malicious code injected by the attacker. This vulnerability demonstrates characteristics consistent with the attack pattern described in the MITRE ATT&CK framework under technique T1059.007 for command and control, and T1068 for exploit for privilege escalation.
The operational impact of CVE-2017-4934 is severe as it enables a guest-to-host privilege escalation attack where a compromised virtual machine can execute arbitrary code with the privileges of the host system. This creates a complete compromise of the host environment, potentially leading to data theft, persistent backdoor installation, or further attacks on the host network. The vulnerability affects users who run untrusted virtual machines or whose virtual environments are already compromised, making it particularly dangerous in multi-tenant environments or scenarios where users have access to virtual machines with elevated privileges. The heap buffer overflow can result in system crashes, data corruption, or complete system compromise depending on the specific memory locations overwritten during the attack.
Mitigation strategies for this vulnerability include immediate patching of affected VMware products to versions 12.5.8 and 8.5.9 respectively, which contain the necessary memory safety fixes and bounds checking improvements. Organizations should also implement network segmentation and access controls to limit the potential impact of guest system compromises, including disabling unnecessary network services within virtual machines. Additional protective measures include monitoring network traffic for suspicious patterns that might indicate exploitation attempts, implementing virtual machine isolation, and maintaining regular backups of critical host systems. The vulnerability highlights the importance of secure coding practices and memory management in virtualization platforms, particularly for components handling network traffic and user input. Security teams should also consider implementing intrusion detection systems to monitor for exploitation attempts and maintain comprehensive incident response procedures for potential compromise scenarios involving virtualized environments.