This is a Sustaining managed bug.
On Windows 7 with User Account Control (UAC) enabled, JVM hangs at getAgentProperties or getSystemProperties after attaching from a "high" IntegrityLevel JVM to a "medium" IntegrityLevel JVM, using Attach API:
attachedVM = com.sun.tools.attach.VirtualMachine.attach(pid);
final Properties systemProperties = attachedVM.getSystemProperties();
In WindowsVirtualMachine.attach is implemented with named pipes.
If named pipe was created with default security properties then windows will not allow process with"medium" IntegrityLevel to be attached to a processwith "high" IntegrityLevel.
Create security properties that allow requested connection.