The correct answer is that the item is only accessible when the device is unlocked and is not backed up to iCloud. This is because the `kSecAttrAccessibleWhenUnlockedThisDeviceOnly` attribute ties the Keychain item’s encryption key to the device’s unique UID, ensuring the data cannot be migrated to another device or restored from any backup—iCloud or iTunes. On the CHFI exam, this tests your understanding of iOS forensic artifacts and how data-at-rest protections affect evidence recovery; a common trap is assuming “ThisDeviceOnly” only blocks iCloud backups, when it actually blocks all backups and device-to-device transfers. Remember the mnemonic “Unlocked and Locked Down”—the item is unlocked only when the screen is on, and locked down so tightly it never leaves the device, not even in a backup.
CHFI Mobile and Malware Forensics Practice Question
This CHFI practice question tests your understanding of mobile and malware forensics. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A security analyst is reviewing the output from a forensic tool examining an iOS Keychain. The analyst finds an entry with the attribute 'kSecAttrAccessible' set to 'kSecAttrAccessibleWhenUnlockedThisDeviceOnly'. What does this indicate?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The item is only accessible when the device is unlocked and is not backed up to iCloud
The attribute 'kSecAttrAccessibleWhenUnlockedThisDeviceOnly' in iOS Keychain indicates that the item can only be accessed when the device is unlocked and is not included in any backup (iCloud or iTunes). This is because the 'ThisDeviceOnly' suffix ties the encryption key to the device's UID, preventing migration to another device or restoration from backup. Option C correctly captures both conditions: accessibility only when unlocked and exclusion from backups.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
The item is backed up to iCloud and can be restored to another device
Why it's wrong here
The 'ThisDeviceOnly' component prevents backup and restoration to other devices.
✗
The item is accessible even when the device is locked
Why it's wrong here
kSecAttrAccessibleWhenUnlockedThisDeviceOnly requires the device to be unlocked.
✓
The item is only accessible when the device is unlocked and is not backed up to iCloud
Why this is correct
This is the correct interpretation of the attribute.
Related concept
Read the scenario before looking for a memorised answer.
✗
The item is stored in the Secure Enclave and cannot be extracted
Why it's wrong here
Keychain items may be protected by Secure Enclave but the attribute does not specify that.
Common exam traps
Common exam trap: answer the scenario, not the keyword
EC-Council often tests the misconception that 'ThisDeviceOnly' only affects backup behavior, when in fact it also prevents restoration to another device, and candidates may confuse 'WhenUnlocked' with 'AfterFirstUnlock' or 'Always', which have different lock-state requirements.
Detailed technical explanation
How to think about this question
The iOS Keychain uses four accessibility classes: 'WhenUnlocked', 'AfterFirstUnlock', 'Always', and 'WhenPasscodeSetThisDeviceOnly', each with a 'ThisDeviceOnly' variant that ties encryption to the device's hardware UID via a key derivation function (KDF). The 'ThisDeviceOnly' variant uses a class key that is wrapped with the device's UID, making the item unrecoverable from backups or on a different device. In a forensic context, this means that even with a full file system image, the item cannot be decrypted without the device's UID and the user's passcode, complicating extraction.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the CHFI exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CHFI question in full detail.
Mobile and Malware Forensics — This question tests Mobile and Malware Forensics — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The item is only accessible when the device is unlocked and is not backed up to iCloud — The attribute 'kSecAttrAccessibleWhenUnlockedThisDeviceOnly' in iOS Keychain indicates that the item can only be accessed when the device is unlocked and is not included in any backup (iCloud or iTunes). This is because the 'ThisDeviceOnly' suffix ties the encryption key to the device's UID, preventing migration to another device or restoration from backup. Option C correctly captures both conditions: accessibility only when unlocked and exclusion from backups.
What should I do if I get this CHFI question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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