Detecting and Mitigating DoS/DDoS Attacks on Protected Objects

Detecting DoS/DDoS Attacks on a Protected Object

Overview: Mitigating DoS/DDoS Attacks on Protected Objects

When you create virtual servers using BIG-IP Local Traffic Manager (LTM), AFM discovers them as protected objects. This discovery makes it easy for you to locate and apply DoS/DDoS protection profiles, and to view the current attack status of each protected object.

DoS/DDoS Protection Profiles

DoS/DDoS protection profiles define the strategies used to detect, and mitigate DoS/DDoS attacks on protected objects. Protection profiles allow you to enable, and configure a wide variety of attack signatures for Network, DNS, and SIP protocols. For most attack signatures, you can allow AFM to manage detection and mitigation thresholds, or you configure attack signature settings manually.

Protection Settings

You can apply the following protection settings to protected objects:

Throughput Capacity

A maximum allowable throughput, in megabits per second, for the protected object. Infinite means no limit.

Protection Profile

A DoS protection profile configured to detect and mitigate DoS/DDoS attack based on known and discovered attack signatures.

Eviction Policy

An Eviction policy controlling the amount of allowable connections, based on specified high and low water marks. Once the high water mark is triggered, a number of eviction strategies can be selected to control how connections are dropped.

IP Intelligence

An IP intelligence policy used to control network access based on client source IP addresses.

Important: For SIP DoS protection, you must also create a SIP profile with SIP Firewall enabled, and attach it to the protected object being protected from SIP DoS attacks.

Configure a DoS/DDoS protection profile

You can create a new DoS protection profile and configure settings to identify, and rate limit possible DNS DoS attacks.

1. On the Main tab, click Security > DoS Protection > Protection Profiles.

   The Protection Profiles list screen opens.

2. Click Create.

   The New Protection Profile screen opens.

3. In the Name field, type the name for the profile.

4. For Threshold Sensitivity, select Low, Medium, or High.

   Low means the automatic threshold calculations are less sensitive to changes in traffic and CPU usage. A lower setting causes the system to adjust the thresholds more slowly over time, but will also trigger fewer false positives. If traffic rates are consistent over time, set this to Medium or High because even a small variation in generally consistent traffic could signal an attack. If traffic patterns vary, set this to Low to get fewer false positives.

5. If you have created a whitelist on the system, from the Default Whitelist list, select the list.

   You can also click Manage Address Lists to jump to the Address Lists screen where you can create or edit address lists.

6. From Families, select Network, DNS, or SIP.

7. At the bottom of the screen, click the selected family.

   The screen displays the attack vectors for the selected family.

8. Click a specific Vector Name, to change the state, threshold or rate increase of the attack vector.

   The Properties page for the attack vector opens to the right of the page.

9. In the Properties pane, from the State list, choose the appropriate enforcement option.

   • Select Mitigate to enforce the configured DoS vector by examining packets, logging the results of the vector, learning patterns, alerting to trouble, and mitigating the attack (watch, learn, alert, and mitigate).
   • Select Detect Only to configure the vector, log the results of the vector without applying rate limits or other actions, and alerting to trouble (watch, learn, and alert).
   • Select Learn Only to configure the vector, log the results of the vector, without applying rate limits or other actions (watch and learn).
   • Select Disabled to disable logging and enforcement of the DoS vector (no stat collection, no mitigation).

10. For Threshold Mode, select whether to have the system determine thresholds for the vector (Fully Automatic), have partially automatic settings (Manual Detection /Auto Mitigation), or, you can control the settings (Fully Manual).

    The settings differ depending on the option you select. Here, we describe the settings for automatic threshold configuration. If you want to set thresholds manually, select one of the manual options and refer to online Help for details on the settings.

11. To allow the DoS vector thresholds to be automatically adjusted, for Threshold Mode, select Fully Automatic (available only for DNS, Flood, SIP, some Fragmentation, and a few other vectors).

    Note: Automatic thresholding is not available for every DoS vector. In particular, for error packets that are broken by their nature, such as those listed under Bad Headers, you must configure them manually.

    1. In the Attack Floor EPS field, type the number of events per second of the vector type to allow at a minimum, before automatically calculated thresholds are determined.

       Because automatic thresholds take time to be reliably established, this setting defines the minimum packets allowed before automatic thresholds are calculated.

    2. In the Attack Ceiling EPS field, specify the absolute maximum allowable for packets of this type before automatically calculated thresholds are determined.

       Because automatic thresholds take time to be reliably established, this setting rate limits packets to the events per second setting, when specified. To set no hard limit, set this to Infinite.

       Unless set to infinite, if the maximum number of packets exceeds the ceiling value, the system considers it to be an attack.

12. To detect IP address sources from which possible attacks originate, enable Bad Actor Detection.

    Note: Bad Actor Detection is not available for every vector.

13. To automatically blacklist bad actor IP addresses, select Add Source Address to Category.

    Important: For this to work, you need to assign an IP Intelligence policy to the appropriate context (device, virtual server, or route domain). For the device, assign a global policy: Security > Network Firewall > IP Intelligence > Policies. For the virtual server or route domain, assign the IP Intelligence policy on the Security tab.

14. From the Category Name list, select the blacklist category to which to add blacklist entries generated by Bad Actor Detection.

15. In the Sustained Attack Detection Time field, specify the duration in seconds after which the attacking endpoint is blacklisted. By default, the configuration adds an IP address to the blacklist after one minute (60 seconds).

16. In the Category Duration Time field, specify the length of time in seconds that the address will remain on the blacklist. The default is 14400 seconds (4 hours).

17. To allow IP source blacklist entries to be advertised to edge routers so they will null route their traffic, select Allow External Advertisement.

    Note: To advertise to edge routers, you must configure a Blacklist Publisher and Publisher Profile at Security > Options > External Redirection > Blacklist Publisher.

18. Click Commit Changes to System at the top of the page.

You have now configured a protection profile to provide custom responses to malformed SIP attacks, SIP flood attacks, and to allow such attacks to be identified in system logs and reports.

Now you need to associate the protection profile with a protected object to apply the settings in the profile to traffic on that protected object.

Modify multiple attack vectors at once

You can modify the State and Threshold Mode of multiple attack vectors protecting the device at one time.

1. On the Main tab, click Security > Dos Protection > Device Protection.

2. Click the Network, DNS, or SIP area at the bottom of the page.

   All of the attack vectors for that familiy appear in the Attack Type list.

3. To modify the state of one or more attack vectors, click the check box next to each attack vector name.

4. From the Set State list at the bottom of the page, select Disable, Learn Only, Mitigate, Detect Only, or Mitigate.

5. Click Commit Changes to System at the top of the page.

6. To modify the threshold mode of one or more attack vectors, click the check box next to each attack vector name.

7. From the Set Threshold Mode list at the bottom of the page, select Fully Automatic, Manual Detection / Auto Mitigation, or Manual.

   Note: To work accurately, using fully-automatic thresholds requires some amount of historical data on the system gathered through observing normal traffic. Therefore, it is recommended that you not enforce auto thresholds directly after installation.

8. Click Commit Changes to System at the top of the page.

You have modified the attack vector State and Threshold Mode of multiple attack vectors.

About AFM auto discovered services

AFM auto discovered services are connection flows that have been processed by an existing protected object. For example, when a forwarding virtual server processes an HTTP connection, the AFM system will create a discovered service for that connection. You can promote an auto discovered service to a protected object, and apply security policies and profiles to security process traffic for that service.

Protected object configuration

To auto discover, a protected object must either have the Service Port option set to *All Ports, or have more than one Destination Address with a specific Service Port. For example:

ltm virtual internal_web {
    destination 192.168.10.0:http
    mask 255.255.255.0
    ip-protocol tcp

ltm virtual internal_net {
    destination 192.168.10.10:any
    mask 255.255.255.255
    ip-protocol tcp

Discovered service auto-naming convention

When a remote client creates a new connection through one of the protect objects, AFM creates a new discovered service object that is eligible for promotion. The AFM system also creates a name for the service by combining the parent protected object name, the IP address and port of the connection. For example:

ltm virtual internal_web_192.168.10.100_80 {
    destination 192.168.10.100:http
    mask 255.255.255.0
    ip-protocol tcp

Enable AFM auto discovery of services

Important: To allow auto discovery, a protected object must either have the Service Port option set to *All Ports, or have more than one Destination Address with a specific Service Port: for example, 10.10.10.0/24 port 80

You can enable AFM service auto discovery on a protected object, allowing you to view, promote, and secure connections being processed by the BIG-IP system.

1. On the Main tab, click Security > Dos Protection > Protected Objects.

2. Click a protected object under the Name column.

   The protected object Properties opens on the right side of the page.

3. Check the Auto Discover Contained Services check box.

4. Click Save at the bottom of the page.

You have enabled auto discovery of services on a protected object.

You can promote a discovered service to protected object status and apply a protection profile.

Promote an AFM discovered service

You can promote a discovered service to protected object status.

1. On the Main tab, click Security > Dos Protection > Protected Objects > Auto Discovered Services/Servers.

2. From the Parent Protected Object list, select a protected object.

   Auto discovered services, and connection related information for each service is displayed.

3. Click the check box next to a discovered service.

4. Click the Promote button.

   The discovered service Properties page displays on the right side of the page.

5. You can modify discovered service properties such as Name, Destination Address, Service Port and Protocol.

6. Click Protection Settings to set a Throughput Capacity, apply a Protection Profile, Eviction Policy or IP Intelligence Policy.

7. Click Save.

Apply a protection profile to a protected object

You must add the DoS protection profile to the protected object to provide enhanced protection from DoS attacks, and track anomalous activity on the BIG-IP system.

1. On the Main tab, click Security > DoS Protection > Protected Objects.

2. Click the name of the protected object (virtual server) to which you want to assign a protection profile.

   The Properties pane opens on the right.

3. In the Protection Settings area, from the Protection Profile list, select the name of the protection profile to assign.

   Note: Ensure a Service Profile is selected to enable the protected object to process application traffic.

4. Click Save.

The DoS protection profile is associated with the protected object and DoS protection is now enabled.

Create a DoS/DDoS logging profile

Create a custom logging profile to log DoS Protection events and send the log messages to a specific location.

1. On the Main tab, click Security > Event Logs > Logging Profiles.

   The Logging Profiles list screen opens.

2. Click Create.

   The Create New Logging Profile screen opens.

3. In the Logging Profile Properties, select the DoS Protection check box.

   The DoS Protection tab opens.

4. In The DoS Protection area, from the Publisher list, select the publisher that the BIG-IP system will use to log DoS events.

5. Click Create.

Assign this DoS Protection logging profile to a protected object.

Logging DoS/DDoS Events for a Protected Object

Assign a logging profile to a protected object when you want the system to log DoS events.

1. On the Main tab, click Security > DoS Protection > Protected Objects.

2. Click the name of the protected object for which you want to log DoS events.

   The Properties pane opens on the right.

3. In the Network & General area, for Logging Profiles, move the logging profile to assign from the Available list into the Selected list.

   You can create, and modify log publishers in System > Logs > Configuration > Log Publishers.

4. Click Save.

The system logs DoS events for the protected object.

You can review DoS event logs at Security > Event Logs > DoS and select the type of DoS event log to view.