Unveiling the Cracks in Virtualization, Mastering the Host System--VMware Workstation Escape

Virtualization escape exploits allow attackers to break out of a virtual machine and execute code on the host system by exploiting vulnerabilities in virtual hardware devices

VMware Workstation’s architecture includes:

• Hypervisor running partly in kernel and user mode
• Virtual hardware devices implemented in user mode process (VMX)
• Guest-to-host communication via physical memory access and I/O operations

Key components for finding virtualization vulnerabilities:

• USB controllers (UHCI, EHCI, XHCI)
• Virtual graphics/SVG components
• Memory management structures (MOB tables, URB structures)
• Endpoint structures and device drivers

Common vulnerability types:

• Use-after-free (UAF) bugs
• Information leaks
• Time-of-check/time-of-use issues
• Buffer overflows
• Arbitrary read/write primitives

Exploitation techniques:

• Heap spraying with SVG shader structures
• Manipulating MOB tables and URB structures
• Leveraging virtual USB device resets
• Using LFH heap features
• Chaining multiple vulnerabilities

Defensive recommendations:

• Keep VMware software updated
• Remove unnecessary virtual devices
• Disable unneeded features like SVA3D
• Study hardware architecture manuals
• Review guest drivers for potential issues

Research methodology:

• Study historical bugs and patches
• Analyze different environments/configurations
• Focus on message/data transmission paths
• Look for timeout and reset conditions
• Understand guest-host interactions