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  5. Creating a Simple Security Policy
Manual Chapter : Creating a Simple Security Policy

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BIG-IP ASM

  • 13.0.1, 13.0.0
Manual Chapter
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Types of security policies

You can create several types of security policies. It is a good idea to understand your options before you begin.

Security policy type Description
Automatic security policy Create a security policy for a web application by having the system examine traffic and create the policy based on statistical analysis of the traffic and the intended behavior of the application. The system stabilizes and enforces the security policy when it processes sufficient traffic over a period of time. You have the option of modifying the policy manually, as well, to speed up policy creation.
Manual security policy Use rapid deployment or an application-ready security policy (pre-configured template) to develop a security policy so you can develop a policy manually. The system creates a basic security policy that you can review and fine-tune. When the security policy includes all the protections that you need, and does not produce any false positives, you can enforce the security policy.
Security policy integrated with vulnerability assessment tool Create a security policy based on integrating the output from a vulnerability assessment tool, such as WhiteHat Sentinel, IBM® AppScan®, Trustwave® App Scanner (Cenzic), Qualys®, Quotium Seeker®, HP WebInspect, or a generic scanner if using another tool. Based on the results from an imported vulnerability report, Application Security Manager™ creates a policy that automatically mitigates the vulnerabilities on your web site. You can also review and fine-tune the policy. When the security policy includes all the protections that you need and does not produce any false positives, you can enforce the security policy.
Parent security policy Create a security policy that can form the basis of other related security policies. This is useful if you have several similar applications for which you want to create security policies. Selected settings in the parent policy are inherited by child policies that you create. By adjusting the parent policy, the child policies are changed as well.
Child security policy Create a security policy that is based on a parent security policy. When you create a child policy, the values for the settings are inherited from the parent. You can edit some of the settings and others can only be changed in the parent policy.
Template security policy Use a template to populate the attributes of a new policy. The template is only used when creating the policy - a security policy is always created based on a user-defined or system-supplied template. Unlike parent policies, the templates do not affect the policy after it is created. If you modify a template, policies created from them in the past are not affected.

Preparing to create a security policy

Before you create and deploy a security policy, you should have an understanding of the application you are trying to protect and why you are trying to protect it. By defining your security problem, you will have an easier time creating and enforcing your security policy.

Some of the questions you might consider before you start are:

  • How strict a policy do you want to create? Fundamental or comprehensive?
  • How many applications do you want ASM to protect? If protecting multiple applications, how similar are they?
  • Do you want to develop one policy for multiple applications, or are the applications different enough that you want to create separate policies for them?
  • Are there a basic set of features that you want to control from a parent policy? Multiple policies can inherit settings from a parent policy.
  • How much traffic and what types of traffic do the applications handle? HTTP, HTTPS, or both?
  • Do the applications have lots of parameters and URLs associated with them? Or are they simple?

A strict, application-specific security policy can potentially take more time and effort to maintain, especially in light of application changes. A generic policy requires less maintenance, even when applied to multiple applications. Some situations will require more extensive tuning of the security policy while in other cases a simple policy will provide effective protection from attacks.

Overview: Creating a simple security policy

You can use the Application Security Manager™ (ASM) to help you build a security policy that is tailored to your environment. ASM can build a policy automatically, or you can do it manually. The policy building tool is called the Real Traffic Policy Builder® (referred to simply as the Policy Builder). The Policy Builder adds suggestions for strengthening a security policy based on settings that you configure, and the characteristics of the traffic going to and from the web application that the system is protecting. If using automatic learning, the system implements the learning suggestions and automatically builds the policy when sufficient traffic and time has passed. If using manual learning, you can review the suggestions and develop the policy adding the policy elements and features you want.

Here we take you through the steps of creating a simple security policy to introduce you to ASM.

Task summary

Creating a simple security policy

Before you can create a security policy, you must perform the minimal system configuration tasks required according to the needs of your networking environment.
You can use Application Security Manager™ to create a robust, yet simple, security policy that is tailored to protect your web application. This is the easiest way to create a security policy.
  1. On the Main tab, click Security > Application Security > Security Policies > Policies List .
    The Policies List screen opens.
  2. Click Create New Policy.
    You only see this button when no policy is selected.
  3. In the Policy Name field, type a name for the policy.
  4. Leave Policy Type, set to Security.
  5. For Policy Template, select Fundamental.
  6. For Virtual Server, click Configure new virtual server to specify where to direct application requests.
    1. For What type of protocol does your application use?, select HTTP, HTTPS, or both.
    2. In the Virtual Server Name field, type a unique name.
    3. In the HTTP Virtual Server Destination field, type the address in IPv4 (10.0.0.1) or IPv6 (2001:ed8:77b5:2:10:10:100:42/64) format, and specify the service port.
      Tip: If you want multiple IP addresses to be directed here, use the Network setting.
    4. In the HTTP Pool Member setting, specify the addresses of the back-end application servers.
    5. From the Logging Profile list, select a profile such as Log illegal requests to determine which events are logged on the system.
  7. In the upper right corner, click Advanced.
    You can use default values for the Advanced settings but it's a good idea to take a look at them.
    • If you selected Fundamental or Comprehensive for the Policy Template, Learning Mode is set to Automatic and Enforcement Mode is set to Blocking.
      Tip: If you need to change these values, set application language to a value other than Auto detect.
    • If you know the Application Language, select it or use Unicode (utf-8).
    • To add specific protections (enforcing additional attack signatures) to the policy, for Server Technologies, select the technologies that apply to the back-end application servers.
    • You can configure trusted IP addresses that you want the security policy to consider safe.
  8. Click Create Policy to create the security policy.
ASM™ creates a security policy that immediately starts protecting your application. The enforcement mode of the security policy is set to Blocking. Traffic that is considered to be an attack such as traffic that is not compliant with HTTP protocol, has malformed payloads, uses evasion techniques, performs web scraping, contains sensitive information or illegal values is blocked. Other potential violations are reported but not blocked.

The system examines the traffic to the web application making suggestions for more specifically building the security policy. The Policy Builder selectively learns new entities like file types, parameters, and cookies used in requests to the application. When ASM processes sufficient traffic, it automatically adds the entities to the security policy, and enforces them.

The system applies a basic set of attack signatures to the security policy and puts them in staging (by default, for 7 days). If you specified server technologies, additional attack signatures are included. ASM reports common attacks discovered by comparison to the signatures but does not block these attacks until the staging period is over and they are enforced. That gives you a chance to be sure that these are actual attacks and not legitimate requests.

Tip: This is a good point at which send some traffic to test that you can access the application being protected by the security policy and check that traffic is being processed correctly by the BIG-IP® system. Send the traffic to the virtual server destination address.

How the security policy is built

When you create a security policy, you have a basic security policy that immediately starts to protect your web application. The Real Traffic Policy Builder® starts examining the application traffic, and fine-tunes the security policy using the guidelines you configured.

The Policy Builder builds the security policy as follows:

  • Adds policy elements and updates their attributes when ASM sees enough traffic from various users
  • Examines application content and creates XML or JSON profiles as needed (if the policy includes JSON/XML payload detection)
  • Configures attack signatures in the security policy
  • Stabilizes the security policy when sufficient sessions over a period of time include the same elements
  • Includes new elements if the site changes

The Policy Builder automatically discovers and populates the security policy with the policy elements (such as file types, URLs, parameters, and cookies). On the Traffic Learning screen, you can monitor general policy building progress, review learning suggestions and deal with those you must handle manually, and see the number of elements that have been included in the policy.

Automatic policy building characteristics

If you create a security policy with the Learning Mode set to Automatic, the Real Traffic Policy Builder® does automatic policy building. This is how it works:

  • The security policy starts out loose, allowing most traffic, then the Policy Builder adds policy elements based on evaluating the traffic.
  • By examining the traffic, the Policy Builder makes learning suggestions that you can review on the Traffic Learning screen to see the suggested additions to the security policy. You can select and examine each suggestion if you want to learn more about it. If using automatic policy building, you can still change the policy manually, or leave it up to the system to make the changes.
  • The system sets the enforcement mode of the security policy to Blocking. Traffic with obvious violations is blocked right away.
  • The system holds attack signatures in staging for 7 days (by default, you can adjust the length of staging): the system checks, but does not block traffic during the staging period. If a request causes an attack signature violation, the system disables the attack signature for the particular element (parameter, JSON or XML profile, or security policy). After the staging period is over, the Policy Builder removes attack signatures from staging if enough traffic from different sessions and different IP addresses was processed. The security policy enforces the enabled signatures and blocks traffic that causes a signature violation.
  • The system enforces elements in the security policy when it has processed sufficient traffic and sessions over enough time, from different IP addresses, to determine the legitimacy of the file types, URLs, parameters, cookies, methods, and so on.
  • After a while, the security policy stabilizes.
  • If the web site for the application changes, the Policy Builder initially loosens the security policy then adds policy elements to the security policy, updates the attributes of policy elements, puts the added elements in staging, and enforces the new elements when traffic and time thresholds are met.

This is generally how the system automatically builds security policies. You can always control the way the security policy works by making changes manually and configuring additional layers of security based on the unique needs of your environment. Also, you have the option of changing the learning mode to Manual.

Reviewing learning suggestions

Before you can see learning suggestions on the system, it needs to have had some traffic sent to it.

After you create a security policy and begin sending traffic to the application, the system provides learning suggestions concerning additions to the security policy based on the traffic it sees. For example, you can have users or testers browse the web application. By analyzing the traffic to and from the application, Application Security Manager™ generates learning suggestions or ways to fine-tune the security policy to better suit the traffic and secure the application.

Note: This task is primarily for building a security policy manually. If you are using the automatic learning mode, this task applies to resolving suggestions that require manual intervention, or for speeding up the enforcement of policy elements.
  1. On the Main tab, click Security > Application Security > Policy Building > Traffic Learning .
    The Traffic Learning screen opens, and lists suggestions based on traffic patterns and violations that the system has detected.
  2. Take a look at the Traffic Learning screen to get familiar with it.
    With no suggestions selected, graphical charts summarize policy activity and you see an enforcement readiness summary on the bottom right.
  3. To change the order in which the suggestions are listed, or refine what is included in the list, use the filters at the top of the column. Click the search icon to see basic and advanced filters.
  4. Review the learning suggestions as follows.
    1. Select a learning suggestion.
      Information is displayed about the action the system will take if you accept the suggestion, and what caused the suggestion.
    2. Select a suggestion to learn more about what caused it by looking at the action, the number of samples it is based on, the violations caused and their violation ratings, and if available, by examining samples of the requests that caused the suggestion.
    3. Select a request to view data about the request on the right, including any violations it generated, the contents of the request itself, and the response (if any).
      By examining the requests that caused a suggestion, you can determine whether it should be accepted.
    4. To add comments about the suggestion and the cause, click the Add Comment icon Add Comment icon to the right of the suggestion commands, and type the comments.
  5. Decide how to respond to the suggestion. You can start with the suggestions that have the highest learning scores, or those which you know to be valid for the application. These are the options.
    Option What happens
    Accept Suggestion The system modifies the policy by taking the suggested action, such as adding an entity that is legitimate. If the entity that triggered the suggestion can be placed in staging (file types, URLs, parameters, cookies, or redirection domains), clicking Accept Suggestion displays a second option, Accept suggestion and enable staging on Matched <<entity>>. Click this option to accept the suggestion and place the matched entity in staging.
    Delete Suggestion The system removes the learning suggestion, but the suggestion reoccurs if new requests cause it. The learning score of the suggestion starts over from zero in that case.
    Ignore Suggestion The system does not change the policy and stops showing this suggestion on the Traffic Learning screen now and in the future. You can view ignored suggestions by filtering by status ignored.
    Note: If you are working in automatic learning mode, when the learning score reaches 100%, the system accepts most of the suggestions, or you can accept suggestions manually at any time. If you are using manual learning, when the learning score reaches 100% (or before that if you know the suggestions are valid), you need to accept the suggestions manually.

    If you know that a suggestion is valid, you can accept it at any time even before the learning score reaches 100%. The ones that reach 100% have met all the conditions so that they are probably legitimate entities.

  6. To put the security policy changes into effect immediately, click Apply Policy.
By default, a security policy is put into an enforcement readiness period for seven days. During that time, you can examine learning suggestions and adjust the security policy making sure that users can access the application. The security policy then includes elements unique to your web application.
It is a good idea to periodically review the learning suggestions on the Traffic Learning screen to determine whether the violations are legitimate and caused by an attack, or if they are false positives that indicate a need to update the security policy. Typically, a wide recurrence of violations at some place in the policy (with a low violation rating and a high learning score) indicates that they might be false positives, and hence the policy should be changed so that they will not be triggered anymore. If the violations seem to indicate true attacks (for example, they have a high violation rating), the policy should stay as is, and you can review the violations that it triggered.

Learning suggestions you must handle manually

Some learning suggestions must be resolved manually even if you are using the Automatic Learning Mode to create a security policy. Suggestions typically require manual intervention if they may have a large impact on the policy or involve changing an attribute that was manually and deliberately set in the policy, such as a disallowed geolocation or a session ID in a URL. In these cases, the system does not change the policy unless you accept the suggestion manually.

You can easily see the suggestions that you need to resolve manually because they are marked with an icon on the Traffic Learning screen as shown in the figure. You can also use the advanced filter to view the suggestions the have Learning Mode set to Manual, and this would list the suggestions you need to resolve.

Manually resolvable suggestions

Suggestions that must be resolved manually

If you are using the Manual Learning Mode, you must resolve all of the suggestions manually.

Reviewing outstanding security policy tasks

You can display a security policy summary including a list of action items. To simplify your work, the system reminds you of required or recommended actions, such as, outstanding configuration and maintenance tasks, and provides links to setup and reporting screens.
  1. On the Main tab, click Security > Overview > Application > Action Items .
    The Action Items screen opens.
  2. Examine the Action Items screen for information about recommended tasks that you need to complete.
    • Review the Suggested Action Items area, which lists system tasks and security policy tasks that should be completed. For example, you can update attack signatures if new ones are available.
    • Click the links to go to the screen where you can perform the recommended action items.
    • Click any security policy task link to open the Summary screen, where you can view and resolve the tasks for that security policy.
  3. In the Quick Links area, click Policies Summary.
    The Policies Summary opens and shows a summary of all the active security policies on the system.
  4. In the Policy Details area, click the links to display details about a security policy.
    • Click the Policy Name to view or edit policy properties.
    • Click a security policy row (not on the policy name) to view Suggested Action Items, Quick Links, and how Policy Builder is operating for that security policy (whether automatically, manually, or disabled).
    • Click a number in the File Types, URLs, Parameters, Cookies, or Redirection Domains column of a security policy to see details about these policy elements.
    • Click the Real Traffic Policy Builder® column to view the learning suggestions for the policy.
If you keep an eye on the summary screens, the system lists the tasks that you should complete to ensure that the security policy is configured completely.

About additional application security protections

The Application Security Manager™ provides additional security protections for a security policy. Some of these protections are automatically enabled depending on the type of security policy you create.

Feature Description and Location
DoS attack prevention Prevents Denial of Service (DoS) attacks based on latency and/or transaction rates (also using behavioral analysis, geolocation, CAPTCHA challenge, heavy URL detection, proactive web scraping detection, and blacklisting). Click Security > DoS Protection . You create a DoS profile with Application Security enabled to configure Layer 7 DoS protection.
Brute force prevention Stops attempts to break in to secured areas of a web application by trying exhaustive, systematic, login combinations. Click Security > Application Security > Anomaly Detection > Brute Force Attack Prevention .
IP Address Intelligence Logs and blocks attacks from IP addresses that are in the IP Address Intelligence Database and are considered to have a bad reputation. Click Security > Application Security > IP Addresses > IP Address Intelligence .
Web scraping detection Mitigates web scraping (web data extraction) on web sites by attempting to determine whether a web client source is human. Click Security > Application Security > Anomaly Detection > Web Scraping .
Geolocation enforcement Lets you specify countries from which users can and cannot access the web application. To set geolocation restrictions, click Security > Application Security > Geolocation Enforcement .
CSRF protection Prevents cross-site request forgery (CSRF) where a user is forced to perform unwanted actions on a web application where the user is currently authenticated. Click Security > Application Security > CSRF Protection .
Sensitive data masking Protects sensitive data in responses such as a credit card number, U.S. Social Security number, or custom pattern. Click Security > Application Security > Data Guard . Create sensitive parameters if needed (they are also masked); click Security > Application Security > Parameters > Sensitive Parameters . As an additional protection, set the Mask Credit Card Numbers in Request Log option in the policy properties.
Anti-virus protection Configures the system as an Internet Content Adaptation Protocol (ICAP) client so that an external ICAP server can inspect HTTP file uploads for viruses before releasing the content to the web server. To set up the ICAP server, click Security > Options > Application Security > Integrated Services > Anti-Virus Protection .
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