Below is contents of filter file.
<plist version="1.0">
<dict>
<key>Filter</key>
<dict>
<key>Executables</key>
<array>
<string>installd</string>
</array>
</dict>
<key>SupportsRoot</key>
<string>1</string>
</dict>
</plist>
The extension was loaded with mobile permission.
How to load it with root permission?