Apple iOS 8 Interim Security Configuration Guide

Password strength is a measure of the effectiveness of a password in resisting guessing and brute-force attacks. The ability to crack a password is a function of how many attempts an adversary is permitted, how quickly an adversary can do each attempt, and the size of the password space. The longer the minimum length of the password is, the larger the password space. Having a too-short minimum password length significantly reduces password strength, increasing the chance of password compromise and resulting device and data compromise. SFR ID: FMT_SMF.1.1 #01

Password complexity or strength refers to how difficult it is to determine a password using a dictionary or brute-force attack. Passwords with sequential or repeating numbers or alphabetic characters (e.g., 456, 987, 222, abc, ddd) are considered easier to crack than random patterns. Therefore, disallowing sequential or repeating numbers or alphabetic characters makes it more difficult for an adversary to discover the password. SFR ID: FMT_SMF.1.1 #42

By allowing the screen capture function, a user has the ability to capture a screen containing sensitive information and then transfer it to an application not authorized to store or process that type of information. For example, the unauthorized app may automatically perform cloud backup to non-DoD servers. If a screen capture containing sensitive information were copied to a location with inadequate protection, there would be a risk that an adversary could obtain it. Disabling the screen capture function will mitigate the risk of leaking sensitive information. SFR ID: FMT_SMF.1.1 #42

A cloud backup feature may gather a user's information, such as PII, or sensitive documents. With this feature enabled, sensitive information will be backed up to the manufacturer's servers and database. This data is stored at a location that has unauthorized employees accessing this data. This data is stored on a server that has a location unknown to the DoD. Disabling this feature mitigates the risk of a backup feature that stores sensitive data on a server that has the ability to be located in a country other than the United States. SFR ID: FMT_SMF.1.1 #42

A cloud document syncing feature may gather user's information, such as PII, or sensitive documents. With this feature enabled, sensitive information will be backed up to the manufacturer's servers and database. This data is stored at a location that has unauthorized employees accessing this data. This data is stored on a server that has a location unknown to the DoD. Disabling this feature mitigates the risk of a backup feature that stores sensitive data on a server that has the ability to be located in a country other than the United States. SFR ID: FMT_SMF.1.1 #42

The iCloud Keychain is an iOS function that will store users' account names and passwords in iCloud, then synchronize this data between the users' Macs, iPhones, and iPads. An adversary may use any of the stored iCloud keychain passwords after unlocking one of the synchronized devices. If a user is synchronizing devices, the user must protect all of the devices to prevent unauthorized use of the passcodes. Moreover, the keychain being transmitted through the cloud opens the possibility that a well-resourced, sophisticated adversary could compromise the cloud-transmitted keychain. Not allowing the iCloud Keychain feature mitigates the risk of the encrypted set of passwords being compromised when transmitted through the cloud or synchronized across multiple devices. SFR ID: FMT_SMF.1.1 #42

When My Photo Stream is enabled, sensitive photos will be automatically uploaded to Apple-specified servers and available on other iOS devices associated with the same Apple ID, provided that the other device also has My Photo Stream enabled. This potentially places sensitive photos on a server outside of DoD's control and potentially makes them available to non-DoD devices. Disabling My Photo Stream mitigates this risk. SFR ID: FMT_SMF.1.1 #42

When iCloud Photo Sharing is enabled, sensitive photos will be automatically uploaded to Apple-specified servers and available on the IOS devices of other users who have accepted invitations to participate in iCloud Photo Sharing. This potentially places sensitive photos on a server outside of DoD's control and potentially makes them available to non-DoD users and devices. Disabling iCloud Photo Sharing mitigates this risk. SFR ID: FMT_SMF.1.1 #42

If the mobile operating system were to display notifications or calendar information on the lock screen, an adversary may be able to gather sensitive data without needing to unlock the device. This adversary may use this gathered intelligence to plan future attacks and possibly a physical attack. By disabling notifications on the lock screen, this prevents sensitive data from being displayed openly on the device’s lock screen. SFR ID: FMT_SMF.1.1 #42

If the mobile operating system were to display notifications or calendar information on the lock screen, an adversary may be able to gather sensitive data without needing to unlock the device. This adversary may use this gathered intelligence to plan future attacks and possibly a physical attack. By disabling notifications on the lock screen, this prevents sensitive data from being displayed openly on the device’s lock screen. SFR ID: FMT_SMF.1.1 #42

On iOS devices, users can access the device's contact database or calendar to obtain phone numbers and other information using a human voice even when the mobile device is locked. Often this information is personally identifiable information (PII), which is considered sensitive. It could also be used by an adversary to profile the user or engage in social engineering to obtain further information from other unsuspecting users. Disabling access to the contact database and calendar in these situations mitigates the risk of this attack. The AO may waive this requirement with written notice if the operational environment requires this capability. SFR ID: FMT_SMF.1.1 #42

On iOS devices, users can access the device's contact database or calendar to obtain phone numbers and other information using a human voice even when the mobile device is locked. Often this information is personally identifiable information (PII), which is considered sensitive. It could also be used by an adversary to profile the user or engage in social engineering to obtain further information from other unsuspecting users. Disabling access to the contact database and calendar in these situations mitigates the risk of this attack. SFR ID: FMT_SMF.1.1 #42

Managed apps have been approved for the handling of DoD-sensitive information. Unmanaged apps are provided for productivity and morale purposes but are not approved to handle DoD-sensitive information. Examples of unmanaged apps include apps for news services, travel guides, maps, and social networking. If a document were to be viewed in a managed app and the user had the ability to open this same document in an unmanaged app, this could lead to the compromise of sensitive DoD data. In some cases, the unmanaged apps are connected to cloud backup or social networks that would permit dissemination of DoD-sensitive information to unauthorized individuals. Not allowing data to be opened within unmanaged apps mitigates the risk of compromising sensitive data. SFR ID: FMT_SMF.1.1 #42

Enterprise books may contain DoD-sensitive information. When enterprise books are backed up, they are vulnerable to attacks on the backup systems and media. Disabling the backup capability mitigates this risk. If such books are lost, accidentally deleted, or corrupted for any reason, they can be easily retrieved from the original source. SFR ID: FMT_SMF.1.1 #42

Storing data with a non-DoD cloud provider may leave the data vulnerable to breach. Disabling non-DoD cloud services mitigates this risk. SFR ID: FMT_SMF.1.1 #42

Exchange email messages are a form of data in transit and thus are vulnerable to eavesdropping and man-in-the-middle attacks. Secure Sockets Layer (SSL), also referred to as Transport Layer Security (TLS), provides encryption and authentication services that mitigate the risk of breach. SFR ID: FMT_SMF.1.1 #42

The iOS Mail app can be configured to support multiple email accounts concurrently. These email accounts are likely to involve content of varying degrees of sensitivity (e.g., both personal and enterprise messages). To prevent the unauthorized and undetected forwarding or moving of messages from one account to another, Mail ActiveSync Exchange accounts can be configured to block such behavior. While users may still send a message from the Exchange account to another account, these transactions must involve an Exchange server, enabling audit records of the transaction, filtering of mail content, and subsequent forensic analysis. SFR ID: FMT_SMF.1.1 #42

An Airdrop feature is a way to send contact information or photos to other users with this same feature enabled. This feature enables a possible attack vector for adversaries to exploit. Once the attacker has gained access to the information broadcast by this feature, he/she may distribute this sensitive information very quickly and without DoD’s control or awareness. By disabling this feature, the risk of mass data exfiltration will be mitigated. SFR ID: FMT_SMF.1.1 #42

Apple's Family Sharing service allows iOS users to create a Family Group whose members have several shared capabilities, including the ability to lock, wipe, play a sound on, or locate the iOS devices of other members. Each member of the group must be invited to the group and accept that invitation. A DoD user's iOS device may be inadvertently or maliciously wiped by another member of their Family Group. This poses a risk that the user could be without a mobile device for a period of time or lose sensitive information that has not been backed up to other storage media. Configuring iOS devices so that their associated Apple IDs are not members of Family Groups mitigates this risk. SFR ID: FMT_SMF.1.1 #42

Sharing of location data is an OPSEC risk because it potentially allows an adversary to determine a DoD user's location and movements and patterns in those movements over time. An adversary could use this information to target the user or to gather intelligence on the user's likely activities. Using commercial cloud services to store and handle location data could leave the data vulnerable to breach, particularly by sophisticated adversaries. Disabling the use of such services mitigates this risk. SFR ID: FMT_SMF.1.1 #42

Security-related parameters are those parameters impacting the security state of the system and include parameters related to the implementation of other IA controls. If these controls are not implemented, the system may be vulnerable to a variety of attacks. The use of mobile device management (MDM) allows an organization to assign values to security-related parameters across all the devices it manages. This provides assurance that the required mobile OS security controls are being enforced and that the device user or an adversary has not modified or disabled the controls. It also greatly increases efficiency and manageability of devices in a large-scale environment relative to an environment in which each device must be configured separately. SFR ID: FMT_SMF.1.1 #42

When a device is unenrolled from MDM, it is possible to relax the security policies that the MDM had implemented on the device. This may cause apps and data to be more vulnerable than they were prior to enrollment. Removing managed apps (and consequently the data they maintain) upon unenrollment mitigates this risk because on appropriately configured iOS devices, DoD-sensitive information exists only within managed apps. SFR ID: FMT_SMF_EXT.1

Configuration profiles define security policies on iOS devices. If a user is able to remove a configuration profile, the user can then change the configuration that had been enforced by that policy. Relaxing security policies may introduce vulnerabilities that the profiles had mitigated. Configuring a profile to never be removed mitigates this risk. SFR ID: FMT_SMF.1.1 #42

The screen lock time-out must be set to a value that helps protect the device from unauthorized access. Having a too-long time-out 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 time-out period of 15 minutes has been selected to balance functionality and security; shorter time-out periods may be appropriate, depending on the risks posed to the mobile device. SFR ID: FMT_SMF.1.1 #02

Citing Government Accountability Office GAO Report 08-536's expression of the definitions of PII from Office of Management and Budget Memorandums 07-16 and 06-19, NIST Special Publication 800-122 states, "PII is any information about an individual maintained by an agency, including (1) any information that can be used to distinguish or trace an individual‘s identity, such as name, social security number, date and place of birth, mother‘s maiden name, or biometric records; and (2) any other information that is linked or linkable to an individual, such as medical, educational, financial, and employment information." The Medical ID in the Health app contains fields for the user's name, date of birth, and medical information, including medical conditions and allergies. It also enables a user to include an personally identifying photograph and list the user's weight, both of which are listed as potential PII in NIST SP 80-122. Avoiding use of the Medical ID mitigates the risk of improper PII disclosure. SFR ID: FMT_SMF.1.1 #42

Apple Pay is a mobile payment technology that enables users to make purchases with their iOS devices, provided that the vendor supports the required Near Field Communications (NFC) interface to Apple Pay. If the payment system is vulnerable to breach, a user's charge cards may be used for unauthorized payments, including charges to government-issued cards. Disabling or avoiding use of Apple Pay mitigates this risk. SFR ID: FMT_SMF.1.1 #42

Several commercial implementations of NFC protocols are vulnerable to man-in-the-middle and replay attacks. If NFC-enabled iOS devices have similar vulnerabilities, this could enable an adversary to perform unauthorized transactions such as mobile payments. Disabling the NFC radio mitigates this risk. SFR ID: FMT_SMF.1.1 #42