ARP requires a license. If you do not have the the ONTAP One license, other licenses are available to use ARP, which differ depending on your version of ONTAP.

You can configure ARP on a per-volume basis using either ONTAP System Manager or the ONTAP CLI.

An effective ransomware detection strategy should include more than a single layer of protection.

An analogy would be the safety features of a vehicle. You don’t rely on a single feature, such as a seatbelt, to completely protect you in an accident. Air bags, anti-lock brakes, and forward-collision warning are all additional safety features that will lead to a much better outcome. Ransomware protection should be viewed in the same way.

While ONTAP includes features like FPolicy, Snapshot copies, and SnapLock to help protect from ransomware, the following information focuses on the ARP on-box feature with machine learning capabilities.

ARP is designed to protect against denial-of-service attacks where the attacker withholds data until a ransom is paid. ARP offers anti-ransomware detection based on:

ARP can detect the spread of most ransomware attacks after only a small number of files are encrypted, take action automatically to protect data, and alert you that a suspected attack is happening.

ARP has two modes:

When you enable ARP, it runs in learning mode. In learning mode, the ONTAP system develops an alert profile based on the analytic areas: entropy, file extension types, and file IOPS. After running ARP in learning mode for enough time to assess workload characteristics, you can switch to active mode and start protecting your data. Once ARP has switched to active mode, ONTAP creates ARP Snapshot copies to protect the data if a threat is detected.

It’s recommended you leave ARP in learning mode for 30 days. Beginning with ONTAP 9.13.1, ARP automatically determines the optimal learning period interval and automates the switch, which may occur before 30 days.

In active mode, if a file extension is flagged as abnormal, you should evaluate the alert. You can act on the alert to protect your data or you can mark the alert as a false positive. Marking an alert as a false positive updates the alert profile. For example, if the alert is triggered by a new file extension and you mark the alert as a false positive, you will not receive an alert the next time that file extension is observed. The command security anti-ransomware volume workload-behavior show shows file extensions that have been detected in the volume. (If you run this command early in learning mode and it shows an accurate representation of file types, you should not use that data as a basis to move to active mode, as ONTAP is still collecting other metrics.)

Beginning in ONTAP 9.11.1, you can customize the detection parameters for ARP. For more information, see manage ARP attack detection parameters.

In active mode, ARP assesses threat probability based on incoming data measured against learned analytics. A measurement is assigned when ARP detects a threat:

In a low threat situation, ONTAP detects an abnormality and creates a Snapshot copy of the volume to create the best recovery point. ONTAP prepends the name of the ARP Snapshot copy with Anti-ransomware-backup to make it easily identifiable, for example Anti_ransomware_backup.2022-12-20_1248.

The threat escalates to moderate after ONTAP runs an analytics report determining if the abnormality matches a ransomware profile. Threats that remain at the low level are logged and visible in the Events section of ONTAP System Manager. When the attack probability is moderate, ONTAP generates an EMS notification prompting you to assess the threat. ONTAP does not send alerts about low threats, however, beginning with ONTAP 9.14.1, you can modify alerts settings. For more information, see Respond to abnormal activity.

You can view information about a threat, regardless of level, in ONTAP System Manager’s Events section or with the security anti-ransomware volume show command.

ARP Snapshot copies are retained for a minimum of two days. Beginning with ONTAP 9.11.1, you can modify the retention settings. For more information, see Modify options for Snapshot copies.

When an attack is suspected, the system takes a volume Snapshot copy at that point in time and locks that copy. If the attack is confirmed later, the volume can be restored using the ARP Snapshot copy.

Locked Snapshot copies cannot be deleted by normal means. However, if you decide later to mark the attack as a false positive, the locked copy will be deleted.

With the knowledge of the affected files and the time of attack, it is possible to selectively recover the affected files from various Snapshot copies, rather than simply reverting the whole volume to one of the Snapshot copies.

ARP thus builds on proven ONTAP data protection and disaster recovery technology to respond to ransomware attacks. See the following topics for more information on recovering data.