Application Security Manager™ (ASM) completely configures the policy building settings according to the selections you make when you create a security policy. These settings are used for both automatic and manual policy building. You can review the settings, and change them later if needed.
The policy building settings control:
There are two levels of policy building settings: basic and advanced. The basic settings are sufficient for most installations, and require less work. Selecting the policy type and learning speed causes ASM to choose reasonable values for the advanced settings.
The advanced level allows you to view and change all of the configuration settings if you want further control over security policy details. However, in most cases, you do not need to change the default values of these settings. F5 recommends that you use the default settings unless you are technically familiar with the web application being protected, and with ASM.
If you are an advanced user, you can review or adjust the settings that the system uses to build or fine-tune a security policy. In most cases, you do not need to change the values of these settings.
|Fundamental||Provides security at a level that is appropriate for most organizations, creating a robust security policy, which is highly maintainable and quick to configure.|
|Enhanced||Provides extra security, creating a security policy with more granularity.|
|Comprehensive||Provides the highest level of security checks, creating a security policy with more granularity, but it may take longer to configure.|
|Vulnerability Assessment||Specifies a security policy that is built using the recommendations from a vulnerability assessment tool. By default, the system does not add explicit entities, leaving that to the tool. (Only available if a vulnerability assessment tool is selected on the Vulnerability Assessments Settings screen.)|
|Custom||Provides the level of security that you specify when you adjust settings, such as which security policy elements are included in the security policy. The policy type changes to Custom if you change any of the default settings for a policy type.|
|Fast||Builds a security policy using lower threshold values for the rules so they are likely to meet the thresholds more quickly; for example, this setting is useful for smaller web sites with less traffic. Selecting this value may create a less accurate security policy.|
|Medium||Builds a security policy based on greater threshold values for the rules. This is the default setting and is recommended for most sites.|
|Slow||Builds a security policy using even higher thresholds for the rules and takes longer to meet them; for example, this value is useful for large web sites with lots of traffic. Selecting this value may result in fewer false positives and create a more accurate security policy.|
By adjusting the policy building settings, you change the way that Application Security Manager™ creates the security policy.
If you are using the automatic learning setting, the Policy Builder builds the security policy automatically in three stages. These stages each have separate sets of settings in the Policy Building Process area of the Learning and Blocking Settings screen. Rules in each stage determine when an element in the security policy moves from one stage to the next.
The rules have different values depending on whether the traffic comes from a trusted or untrusted source. The system generally considers trusted traffic, and the policy elements it contains, to be legitimate, and adds them to the policy more quickly than it does those in untrusted traffic.
You can adjust the values for the rules by changing the Learning Speed setting. Slow learning speed causes the system to create the policy by looking at more traffic, over more time, and from more different IP addresses, so the values in the rules are higher. Fast learning speed causes the system to build the policy from fewer requests, from only one IP address, and the values you see in the rules are lower.
Advanced users can view and change the conditions under which the Policy Builder modifies the security policy during any of the three stages. Changing the values in any of the rules (to values not matching any of the default values) also changes the learning speed to the Custom policy type (instead of Fast, Medium, or Slow).
Automatic policy building is enabled when you have Learning Mode set to Automatic. In this case, the Policy Builder builds the security policy in three stages:
During this stage, the Policy Builder identifies legitimate application usage based on repeated behavior from sufficient different user sessions and IP addresses, over a period of time. The system makes learning suggestions on ways to update the security policy. Based on wildcard matches, Policy Builder suggests adding the legitimate policy entities (putting most into staging to learn their properties), and disabling violations that are probably false positives. If you are using automatic learning, the Policy Builder implements the suggestions when policy building rules are met, updates the security policy, and enforces the entities. If you are using manual learning and want to enhance the security policy, you can address each of the suggestions that the system made.
For example, when the Policy Builder sees the same file type, URL, parameter, or cookie from enough different user sessions and IP addresses over time, it then makes learning suggestions. If you are using automatic learning, over time, the Policy Builder adds the entities to the security policy. If you are using manual learning, you can accept, delete, or ignore the suggested additions to the security policy.
Rules that tighten a security policy are applicable only when you are using automatic learning. During this stage, the Policy Builder refines the security policy elements until the number of security policy changes stabilizes. For example, the Policy Builder enforces an entity type after it records a sufficient number of unique requests and sessions, for different IP addresses, over a sufficient length of time since the last time an explicit file type, URL, or parameter was added to the security policy, or a change was made to any of its attributes.
Similarly, the Policy Builder enforces the entity (takes them out of staging) after it records a sufficient number of unique requests and sessions from different IP addresses, over a sufficient length of time for a particular file type, URL, parameter, or cookie.
When the traffic to the application no longer includes new elements, and the Policy Builder has enforced the policy elements, the security policy is considered stable.
This stage occurs after the security policy is stable, and is only relevant when using automatic learning. If the Track Site Changes setting is enabled and the Policy Builder discovers changes to the web application, it logs the change (Site change detected) and temporarily loosens the security policy to make the necessary suggestions or adjustments. When the Policy Builder stabilizes the added elements, it re-tightens the security policy.
Although it is not recommended, you can disable the Track Site Changes option. If you do, the Policy Builder continues to monitor traffic and note whether the web application has changed, and if it has, makes suggestions for loosening the policy. However, the security policy is not updated unless you manually change it.
Policy building rules specify how a security policy is built. When you create the security policy, values for the rules are set according to the policy type you select. Advanced users can view and modify the rules, for trusted and untrusted traffic, if your application has unique requirements. In most cases, you do not need to change the values of the rules.
|Fast||Use if your application supports a small number of requests from a small number of sessions; for example, useful for web sites with less traffic. Policy Builder requires fewer unique traffic samples to make decisions in Automatic Learning Mode, or to reach a high learning score. However, choosing this option may present a greater chance of adding false entities to the security policy.|
|Medium||Use if your application supports a medium number of requests, or if you are not sure about the amount of traffic on the application web site. This is the default setting.|
|Slow||Use if your application supports a large number of requests from many sessions; for example, useful for web sites with lots of traffic. Policy Builder requires a large amount of unique traffic samples to make decisions in Automatic Learning Mode, or to reach a high learning score. This option creates the most accurate security policy, but it takes Policy Builder longer to collect the statistics.|
The system now builds the security policy with the adjusted security policy rules.
|Fundamental||Provides security at a level that is appropriate for most organizations, creating a robust security policy, which is highly maintainable and quick to configure.|
|Enhanced||Provides extra customization, creating a security policy with more granularity.|
|Comprehensive||Provides the highest level of customization, creating a security policy with more granularity, but it may take longer to configure.|
|Custom||Provides the level of security that you specify when you adjust settings such as which security policy elements are included in the security policy. You cannot choose this type but the policy type changes to Custom if you adjust any of the default settings for a policy.|
The elements that are currently in the security policy remain in the policy. From this point on, the security policy is built according to the new policy type you have selected.
In a security policy, you can include a list of IP addresses that you want the system to consider safe or trusted. Take care when specifying trusted IP addresses. Trusted IP addresses are typically internal IP addresses to which only trusted users have access.
Application Security Manager™ (ASM) processes traffic from trusted clients differently than traffic from untrusted clients. For clients with trusted IP addresses, the rules are configured so that ASM™ requires less traffic (by default, only 1 user session) to update the security policy or make suggestions about adding an entity or making other changes. It takes more traffic from untrusted clients to change or suggest changes to the security policy (for example, if using the default values).
If the Learning Mode is Manual, the login page is added to the learning suggestions on the Traffic Learning screen where you can add it to the policy. The login pages in the security policy are included in the Login Pages List.
When using automatic learning, you can instruct the system to examine and classify the content of learned parameters. If the system detects legitimate XML or JSON data in parameters, the system adds (or suggests adding) XML or JSON content profiles to the security policy and configures them using the data found.
Integer parameters are parameters with a data type that is numeric and can include only whole numbers. If a security policy is learning parameters (when Learn New Parameters is set to Selective or Add All Entities), you can specify whether the Policy Builder suggests adding integer parameters to the security policy. This option is available only when the learning mode is set to automatic.
When the Application Security Manager™ receives a request that includes an entity (for example, a URL) containing an integer parameter, the system collects the parameter value from the web application’s response to the request and suggests adding it to the security policy.
Dynamic parameters are those whose values are regenerated when the user accesses an application. For example, a session ID is a dynamic parameter, and it is linked to a user session. The system can extract dynamic parameters from parameters, URLs, and file types. You can specify the conditions under which the Policy Builder suggests adding dynamic parameters to the security policy. This option is available only when the learning mode is set to automatic.
|All HIDDEN Fields||Adds to the security policy all hidden form input parameters, seen in responses, as dynamic content value parameters.|
|Using statistics - FORM parameters||Adds parameters from forms as dynamic content value parameters.|
|Using statistics - link parameters||Adds parameters from links as dynamic content value parameters.|
|Statistics: Configure parameters as dynamic if <num>...||Specifies the number (<num>) of unique value sets that must be seen for a parameter before the system considers it a dynamic content value. The default value is 10.|
When the Application Security Manager™ receives a request that includes an entity (for example, a file extension or URL) containing a dynamic parameter, the system collects the parameter value or name from web application’s response to the request and suggests adding it to the security policy.
When using automatic policy building, the system automatically simplifies your security policy by combining several similarly named explicit entities into wildcard entities. For example, multiple parameters beginning with param are combined into param*. You can specify which entities should be collapsed and after how many occurrences.
If a request causes the Modified domain cookie(s) violation, the system changes their type from “enforced” to “allowed” (in the GUI they are moved between the tabs).
In cases where you want all cookies to be enforced, the * cookie wildcard must be an allowed cookie. If you do not want all cookies to be enforced, the * cookie wildcard must be an enforced cookie. In either case, set Learn New Cookies to Never (wildcard only) and clear the Learn and enforce new unmodified cookies check box.
When building a security polcy using automatic or manual learning, the system has reasonable limits for the maximum number of file types, URLs, parameters, cookies, and redirection domains that the system can learn and add to the security policy. These limits work fine for most situations. You can adjust the limits, if needed. Note that you can always add an entity manually even after the limits are reached.
When using automatic learning, you can instruct the system to examine and classify the content of requests to URLs. If the system detects legitimate XML, JSON, or Google Web Toolkit (GWT) data in requests to URLs configured in the security policy, the system adds XML, JSON, or GWT content profiles to the security policy and configures them using the data found.
For security policies that are tracking URLs (policy types other than fundamental), the system adds a wildcard URL instead of explicit URLs for commonly used file types. You can adjust the list of file types that are changed to wildcard URLs.
If you are using automatic learning to build a policy, you can have the system examine responses as well as requests for entities to include in the security policy. This is called learning from responses, and the system does this by default. You may want to learn from responses because a response might include more information about the web application than is found in the request, or if you want to have the system learn login pages automatically.
You can disable this setting if your application does not need to examine responses for entities to add to the security policy, or if the application does not use dynamic parameters.
If you disabled the Learn from responses check box, the Policy Builder never adds to the security policy elements found in responses. If the check box is enabled, the Policy Builder adds elements found in valid responses to the security policy (meaning those that do not generate violations).
Application Security Manager™ provides full functionality, and performs full policy inspection, and holds in memory information about the configuration of entities that are included in a security policy. In rare cases, such as on systems with limited memory or when instructed to do so by F5 Support, you might need to disable full policy inspection.
If you disable the Full Policy Inspection check box, the system does not store all the information about the policy elements in memory, thus it enables memory optimization. However, you lose some functionality. When the setting is disabled, the system cannot collapse URLs, WebSocket URLs, parameters, or content profiles (the collapse settings are cleared, become unavailable, and cannot be changed). The system no longer performs classification for parameters, URLs, or WebSocket URLs.
Disabling full policy inspection causes pabnagd (policy building daemon) to restart in 5 minutes. The delay allows time to disable the check box on more than one policy. The restart does not affect traffic throughput.
When using automatic or manual learning, the system learns from legitimate traffic including transactions that return response codes of 1xx, 2xx, and 3xx. These classes of codes are added by default to the policy building settings. You can change which response codes are listed, or add specific response codes, such as those used by the web application you are protecting.
|1xx||All informational responses (the request was received; continuing to process it). Included by default.|
|2xx||All successful responses (the request was received, understood, accepted, and processed successfully). Included by default.|
|3xx||All redirection (the client needs to take additional action on the request). Included by default.|
|4xx||Server failed to fulfill the response as a result of client syntax or input errors.|
|5xx||All server error responses (the server failed to fulfill a request).|
|Specific codes such as 100, 306, 400, or 404||Refer to your web application or the Hypertext Transfer Protocol -- HTTP/1.1 specification (RFC-2616).|
You can use the Real Traffic Policy Builder® to automatically build a security policy in two ways: with automatic learning or manual learning. When you set Learning Mode to automatic, the Policy Builder makes suggestions on how to update the security policy and updates the security policy when the policy building rules are met. It does this by automatically enforcing the suggested changes, adding file types, URLs, parameters, and so on for the web application. The Policy Builder also operates when you set Learning Mode to manual. In this case, the Policy Builder examines traffic, and makes suggestions on what to add to the security policy or what to change in the policy settings but you have to implement them.
|Option||Who builds the security policy?|
|Automatic||The Policy Builder. It examines traffic, makes suggestions, and enforces most suggestions after sufficient traffic over a period of time from various users makes it reasonable to add them. You may have to enforce a few suggestions manually, and you have the option of enhancing the policy manually.|
|Manual||The Policy Builder and you together. The Policy Builder examines traffic and makes suggestions on what to add to the security policy. You need to manually handle the suggestions on the Traffic Learning screen, and optionally adjust the security policy.|
|Disabled||You. The Policy Builder does not do any learning for the security policy, and makes no suggestions. Based on your knowledge of the web application, you can manually add entities to the security policy and adjust the policy building settings.|
If you set learning mode to automatic, the Policy Builder automatically discovers and populates the security policy with the policy elements (such as file types, URLs, parameters, and cookies). If you are using manual learning, the Policy Builder examines traffic and makes suggestions on ways to adjust the security policy; changes are implemented only when you approve them. You can manually accept, delete, or ignore the suggestions on the Traffic Learning screen.
If you disable the learning mode, all learning suggestions are deleted and no more learning takes place; the security policy remains the same unless you manually change it. If you enable manual or automatic learning later, the learning process starts over. Regardless of the learning mode, you can always monitor the policy and manually change it.
If you have adjusted the policy building settings and want to replace those values, you can restore them to the system default values.