Windows 10 Mobile must protect data at rest on removable storage media.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-70097	MSWM-10-201705	SV-84719r1_rule		High

Description
The MOS must ensure the data being written to the mobile device's removable media is protected from unauthorized access. If data at rest is unencrypted, it is vulnerable to disclosure. Even if the operating system enforces permissions on data access, an adversary can read removable media directly, thereby circumventing operating system controls. Encrypting the data ensures confidentiality is protected even when the operating system is not running. With Windows 10 Mobile there is not a capability to encrypt data on removable storage therefore the mitigation is to disable the use of removable storage in the DoD. SFR ID: FMT_SMF_EXT.1.1 #26

Description

The MOS must ensure the data being written to the mobile device's removable media is protected from unauthorized access. If data at rest is unencrypted, it is vulnerable to disclosure. Even if the operating system enforces permissions on data access, an adversary can read removable media directly, thereby circumventing operating system controls. Encrypting the data ensures confidentiality is protected even when the operating system is not running. With Windows 10 Mobile there is not a capability to encrypt data on removable storage therefore the mitigation is to disable the use of removable storage in the DoD. SFR ID: FMT_SMF_EXT.1.1 #26

STIG	Date
Microsoft Windows 10 Mobile Security Technical Implementation Guide	2016-09-26

Details

Check Text ( C-70573r1_chk )
Review Windows 10 Mobile configuration settings to determine if data in the mobile device's removable storage media is encrypted. If feasible, use a spare device to confirm that data-at-rest protection is enabled for removable storage media. This validation procedure is performed on both the MDM administration console and the Windows 10 Mobile device. On the MDM administration console: 1. Ask the MDM administrator to verify the phone compliance policy. 2. Find the setting for "allow removable storage". 3. Verify that setting restriction is turned off/disallowed. On a Windows 10 Mobile device that contains a microSD slot and has a microSD card inserted: 1. Launch "Settings". 2. Tap on "System" and then tap on "Storage". 3. Look for a drive called "This Device" which shows how much space has been used. 4. Verify that even if an SD card is mounted in the device there is not a drive called "SD Card" listed directly below the "This Device" drive. If the MDM does not have a policy enforcement that disables the use of removable storage or if on the phone an SD Card is listed under "This Device" on the "Storage" screen, this is a finding.

Check Text ( C-70573r1_chk )

Review Windows 10 Mobile configuration settings to determine if data in the mobile device's removable storage media is encrypted. If feasible, use a spare device to confirm that data-at-rest protection is enabled for removable storage media.

This validation procedure is performed on both the MDM administration console and the Windows 10 Mobile device.

On the MDM administration console:

1. Ask the MDM administrator to verify the phone compliance policy.
2. Find the setting for "allow removable storage".
3. Verify that setting restriction is turned off/disallowed.

On a Windows 10 Mobile device that contains a microSD slot and has a microSD card inserted:

1. Launch "Settings".
2. Tap on "System" and then tap on "Storage".
3. Look for a drive called "This Device" which shows how much space has been used.
4. Verify that even if an SD card is mounted in the device there is not a drive called "SD Card" listed directly below the "This Device" drive.

If the MDM does not have a policy enforcement that disables the use of removable storage or if on the phone an SD Card is listed under "This Device" on the "Storage" screen, this is a finding.

Fix Text (F-76333r2_fix)
Configure the MDM system to enforce a policy which configures the "allow removable storage" policy to be disabled for Windows 10 Mobile devices. Deploy the MDM policy to managed devices.