Filesystem:/Applications/CheckerBoard.app

Summary
This (hidden) application is usually accessed by powering off the device, then after plugging in a charger, start holding down the volume up button and home button. It is present on all iOS 10.3 devices.

It looks to be sending data to https://idiagnostics.apple.com, however due to certificate pinning, the data being sent is unknown. It is known to connect to AST2, an internal diagnostics web app, for diagnostics.

Localization strings
Extracting its English localization strings yields these:  /* ARE_YOU_SURE */ Are you sure you want to exit Diagnostics?

/* CANCEL */ Cancel

/* CHOOSE_OTHER_FOOTER */ Choose Another Network

/* CHOOSE_WIFI_HEADER */ Choose a Wi‑Fi Network

/* CHOOSE_WLAN_HEADER */ Choose a WLAN Network

/* COULD_NOT_FIND_NETWORK_TITLE */ Could not find the network “%@”

/* DIAGNOSTICS */ Diagnostics

/* DIAGNOSTICS_DESCRIPTION */ Diagnostics allow Apple to identify potential hardware and software issues with this device.

/* DISMISS */ Dismiss

/* DONE */ Done

/* EMERGENCY_CALL */ Emergency Call

/* ENCRYPTED_NETWORK_PROMPT */ Enter the password for “%@”

/* ENCRYPTED_NETWORK_TITLE */ Enter Password

/* EXIT_DIAGNOSTICS */ Exit Diagnostics

/* FAILED_NETWORK_PROMPT */ Failed to join “%@”

/* INCORRECT_PASSWORD_TITLE */ Incorrect password for “%@”

/* JOIN */ Join

/* JOINED_NETWORK_PROMPT */ Joined network “%@”

/* JOINING_NETWORK_PROMPT */ Joining “%@”…

/* NEXT */ Next

/* NONE */ None

/* NO_NETWORK_CONNECTION_MESSAGE_WIFI */ The Wi‑Fi network you selected is not providing an Internet connection. Change your settings or choose a different network.

/* NO_NETWORK_CONNECTION_MESSAGE_WLAN */ The WLAN network you selected is not providing an Internet connection. Change your settings or choose a different network.

/* NO_NETWORK_CONNECTION_TITLE */ No Network Connection

/* OK */ OK

/* OTHER_NETWORK_NAME */ Name

/* OTHER_NETWORK_PLACEHOLDER */ Network Name

/* OTHER_NETWORK_PROMPT */ Enter network information

/* OTHER_NETWORK_TITLE */ Other Network

/* PASSWORD */ Password

/* SECURITY */ Security

/* SERIAL_NUMBER */ Serial Number

/* SHUT_DOWN */ Shut Down

/* START_DIAGNOSTICS */ Start Diagnostics

/* TEMPERATURE */ Temperature

/* THERMAL_ALERT_STRING_IPAD */ iPad needs to cool down before you can use it.

/* THERMAL_ALERT_STRING_IPHONE */ iPhone needs to cool down before you can use it.

/* THERMAL_ALERT_STRING_IPOD */ iPod needs to cool down before you can use it.

/* TRY_AGAIN_MESSAGE */ Please try again later.

/* UNABLE_TO_JOIN_NETWORK_TITLE */ Unable to join the network “%@”

/* UNABLE_TO_JOIN_TITLE */ Unable to join “%@”

/* WEP */ WEP

/* WIFI_SETTINGS */ Wi‑Fi Settings

/* WLAN_SETTINGS */ WLAN Settings

/* WPA */ WPA

/* WPA2 */ WPA2

/* WPA2_ENTERPRISE */ WPA2 Enterprise

/* WPA_ENTERPRISE */ WPA Enterprise

Folders

 * _CodeSignature/
 * ar.lproj/
 * ca.lproj/
 * cs.lproj/
 * da.lproj/
 * de.lproj/
 * el.lproj/
 * en.lproj/
 * en_AU.lproj/
 * en_GB.lproj/
 * es.lproj/
 * es_419.lproj/
 * fi.lproj/
 * fr.lproj/
 * fr_CA.lproj/
 * he.lproj/
 * hi.lproj/
 * hr.lproj/
 * hu.lproj/
 * id.lproj/
 * it.lproj/
 * ja.lproj/
 * ko.lproj/
 * ms.lproj/
 * nl.lproj/
 * no.lproj/
 * pl.lproj/
 * pt.lproj/
 * pt_PT.lproj/
 * ro.lproj/
 * ru.lproj/
 * sk.lproj/
 * sv.lproj/
 * th.lproj/
 * tr.lproj/
 * uk.lproj/
 * vi.lproj/
 * zh_CN.lproj/
 * zh_HK.lproj/
 * zh_TW.lproj/

Files

 * Assets.car
 * CheckerBoard
 * Entitlements.plist
 * Info.plist
 * PkgInfo