CSP causing delay in acoustic sound from the encrypted pin-pad

Products

• Critical System Protection

Issue/Introduction

It has been reported that on ATM machine with Windows 10 OS and CSP 8.0.x there is a delay in playing a sound when pin pad is used. 

The issue occurred after installing the Windows Updates below:

KB4494175
KB4520724
KB4537806

If the is output from the headphone jack, the delay does not occur.

This issue has been observed with ATM from KEBA manufacturer. 

Cause

The delay was caused by increased number of registry access calls. 

Environment

Windows 10 IoT

Realtech Audio Sound Card

Resolution

1. Modify Prevention Policy and add the following registry key to writable resource list in Default Windows Programs and Services def_winsvc_ps sandbox. 

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\MMDevices\Audio\Render*

2. "Disable" the Audio Enhancement for the Audio Device