Apple iOS must be configured to lock the display after 15 minutes (or less) of inactivity.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-81759	AIOS-12-000300	SV-96473r1_rule		Medium

Description
The screen lock timeout must be set to a value that helps protect the device from unauthorized access. Having a too-long timeout would increase the window of opportunity for adversaries who gain physical access to the mobile device through loss, theft, etc. Such devices are much more likely to be in an unlocked state when acquired by an adversary, thus granting immediate access to the data on the mobile device. The maximum timeout period of 15 minutes has been selected to balance functionality and security; shorter timeout periods may be appropriate depending on the risks posed to the mobile device. Satisfies: PP-MDF-301030, PP-MDF-301040 SFR ID: FMT_SMF_EXT.1.1 #2a & #2b

Description

The screen lock timeout must be set to a value that helps protect the device from unauthorized access. Having a too-long timeout would increase the window of opportunity for adversaries who gain physical access to the mobile device through loss, theft, etc. Such devices are much more likely to be in an unlocked state when acquired by an adversary, thus granting immediate access to the data on the mobile device. The maximum timeout period of 15 minutes has been selected to balance functionality and security; shorter timeout periods may be appropriate depending on the risks posed to the mobile device. Satisfies: PP-MDF-301030, PP-MDF-301040 SFR ID: FMT_SMF_EXT.1.1 #2a & #2b

STIG	Date
Apple iOS 12 Security Technical Implementation Guide	2018-11-28

Details

Check Text ( C-81539r1_chk )
Review configuration settings to confirm the screen lock timeout is set to 15 minutes or less. This check procedure is performed on both the Apple iOS management tool and the Apple iOS device. Note: If an organization has multiple configuration profiles, the check procedure must be performed on the relevant configuration profiles applicable to the scope of the review. In the management tool, verify the sum of the values assigned to "Maximum Auto-Lock time" and "Grace period for device lock" is between 1 and 15 minutes. Alternatively, locate the text "maxGracePeriod" and "maxInactivity" and ensure the sum of their integer value is between 1 and 15 in the configuration profile (.mobileconfig file). For example: "maxGracePeriod 5 maxInactivity 5" Here, 5 + 5 = 10; this meets the requirement. On the Apple iOS device: 1. Open the Settings app. 2. Tap "General". 3. Tap "Profiles & Device Management". 4. Tap the Configuration Profile from the iOS management tool containing the password policy. 5. Tap "Restrictions". 6. Tap "Passcode". 7. Verify the sum of the "Max grace period" and "Max inactivity" values is less than 15 minutes. Note: On some iOS devices, it is not possible to have a sum of exactly 15. In these cases, the sum must be less than 15. A sum of 16 does not meet the requirement. On the management server, if the sum of the "Max grace period" and "Max inactivity" values is not between 1 and 15 minutes in the iOS management tool, if the sum of the values assigned to "maxGracePeriod" and "maxInactivity" is not between 1 and 15 minutes in the configuration profile, or on the iOS device, if the sum of the values assigned to "Max grace period" and "Max inactivity" is not between 1 and 15 minutes, this is a finding.

Check Text ( C-81539r1_chk )

Review configuration settings to confirm the screen lock timeout is set to 15 minutes or less.

This check procedure is performed on both the Apple iOS management tool and the Apple iOS device.

Note: If an organization has multiple configuration profiles, the check procedure must be performed on the relevant configuration profiles applicable to the scope of the review.

In the management tool, verify the sum of the values assigned to "Maximum Auto-Lock time" and "Grace period for device lock" is between 1 and 15 minutes.

Alternatively, locate the text "maxGracePeriod" and "maxInactivity" and ensure the sum of their integer value is between 1 and 15 in the configuration profile (.mobileconfig file). For example:

"maxGracePeriod
5
maxInactivity
5"

Here, 5 + 5 = 10; this meets the requirement.

On the Apple iOS device:
1. Open the Settings app.
2. Tap "General".
3. Tap "Profiles & Device Management".
4. Tap the Configuration Profile from the iOS management tool containing the password policy.
5. Tap "Restrictions".
6. Tap "Passcode".
7. Verify the sum of the "Max grace period" and "Max inactivity" values is less than 15 minutes.

Note: On some iOS devices, it is not possible to have a sum of exactly 15. In these cases, the sum must be less than 15. A sum of 16 does not meet the requirement.

On the management server, if the sum of the "Max grace period" and "Max inactivity" values is not between 1 and 15 minutes in the iOS management tool, if the sum of the values assigned to "maxGracePeriod" and "maxInactivity" is not between 1 and 15 minutes in the configuration profile, or on the iOS device, if the sum of the values assigned to "Max grace period" and "Max inactivity" is not between 1 and 15 minutes, this is a finding.

Fix Text (F-88607r1_fix)
Install a configuration profile to lock the device display after 15 minutes (or less) of inactivity. This is done by setting "Maximum Auto-Lock time" and "Grace Period for device lock" so the sum of their values is between 1 and 15 minutes.