Media Player Classic playback cuts out audio inside confidential box

[HqT65W6R]

Describe what you noticed and did

• Media Player Classic x64 can stop playback when remaining idle and not repeat track playback
• Media Player Classic x64 starts with audio not working every once in a while
• Media Player Classic x64 does not start with DropAdminRights=y without Cryptorgraphic Service errors (which is probably related to a recently reported issue mentioned in the latest change log for not-yet released Sandboxie)

Steps to reproduce:

1. Use Sandboxie Classic 5.70
2. Install madVR test build 207 outside of Sandboxie (see download link in appropriate section below)
3. Configure Media Player Classic (MPC-HC64.exe) to use Sandboxie.exe provided on the bottom

How often did you encounter it so far?

Once every 3 launches

Expected behavior

Playback continues as usual

Affected program

Media Player Classic x64, madVR

Download link

https://github.com/clsid2/mpc-hc/releases/download/2.3.6/MPC-HC.2.3.6.21.x64.zip
https://www.videohelp.com/download/madVR09217.zip

Where is the program located?

The program is installed both inside and outside the sandbox.

Did the program or any related process close unexpectedly?

No, not at all.

Crash dump

No response

What version of Sandboxie are you running now?

5.70

Is it a new installation of Sandboxie?

I recently did a new clean installation.

Is it a regression from previous versions?

No response

In which sandbox type you have this problem?

In a security hardened sandbox (orange sandbox icon).

Can you reproduce this problem on a new empty sandbox?

I can confirm it also on a new empty sandbox.

What is your Windows edition and version?

Windows 24H2 26100.2152

In which Windows account you have this problem?

A local account (Administrator).

Please mention any installed security software

Not relevant

Did you previously enable some security policy settings outside Sandboxie?

• Enabled flags for DEP, ATL Thunk, SEHOP, ASLR, Heap Termination on Corruption, Bottom Up ASLR, High Entropy ASLR, and Control Flow Guard,
• Disabled Extension Point, remote loads, low integrity loads, non-system fonts.

Trace log

No response

Sandboxie.ini configuration

Global:
SandboxieLogon=y
CoverBoxedWindows=y
OpenSamEndpoint=n
HideNonSystemProcesses=y
HideSbieProcesses=y
HideOtherBoxes=y
HideDiskSerialNumber=y

Box-Specific:
ForceProcess=madTPG.exe
ForceProcess=madHCCtrl.exe
ForceProcess=MPC-HC64.exe
DropAdminRights=madTGP.exe,y
DropAdminRights=madHCCtrl.exe,y
FakeAdminRights=MPC-HC64.exe,y
BlockScreenCapture=MPC-HC64.exe,y
UseSecurityMode=y
UsePrivacyMode=y
HideNetworkAdapterMAC=y
RestrictDevices=y
SysCallLockDown=y
UseRuleSpecificity=y
RandomRegUID=y
ConfidentialBox=y
DenyHostAccess=audiodg.exe,n
NotifyStartRunAccessDenied=n
ClosedFilePath=InternetAccessDevices

[offhub]

Media Player Classic x64 can stop playback when remaining idle and not repeat track playback

I haven't encountered this issue. It would be helpful if you could explain how to reproduce it.

Media Player Classic x64 starts with audio not working every once in a while

This issue occurs when a video is opened in MPC-HC while it is not in focus. The same problem exists in a standard box as well. Can you confirm this?

Workaround:

OpenWinClass=*

Media Player Classic x64 does not start with DropAdminRights=y without Cryptorgraphic Service errors (which is probably related to a recently reported issue mentioned in the latest change log for not-yet released Sandboxie)

This issue will be fixed in the upcoming version 1.15.1/5.70.1.

[HqT65W6R]

Yes, it does appear that out-of-focus is a factor in top 2 issues I mention.

[DavidXanatos]

@offhub if the template changes in 1.15.1 have fixed this then we can close the issue?

[DavidXanatos]

how to reproduce the crypto errors? open a https video stream or alike? demo link please

[offhub]

@DavidXanatos The title of this issue can be misleading. When videos are started playing while the media player is out of focus, they play without sound, and to fix this, OpenWinClass=* needs to be used. The only problem is that when a program is specified for this setting, OpenWinClass=MPC-HC64.exe,*, it doesn't produce the same result. The MMCSS setting added to the templates has no relevance to this issue

how to reproduce the crypto errors? open a https video stream or alike? demo link please

This issue has already been fixed in version 1.15.1.

Sandboxie/CHANGELOG.md

Line 35 in f97cce1

- fixed Sandboxie crypto fails to start in red boxes