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CAPEC-87: Forceful Browsing

 
Forceful Browsing
Definition in a New Window Definition in a New Window
Attack Pattern ID: 87
Abstraction: Standard
Status: Draft
Completeness: Complete
Presentation Filter:
+ Summary

An attacker employs forceful browsing to access portions of a website that are otherwise unreachable through direct URL entry.

Usually, a front controller or similar design pattern is employed to protect access to portions of a web application.

Forceful browsing enables an attacker to access information, perform privileged operations and otherwise reach sections of the web application that have been improperly protected.

+ Attack Execution Flow
Explore
  1. Spider:

    Using an automated tool, an attacker follows all public links on a web site. He records all the links he finds.

    Attack Step Techniques

    IDAttack Step Technique DescriptionEnvironments
    1

    Use a spidering tool to follow and record all links

    env-Web
    2

    Use a proxy tool to record all links visited during a manual traversal of the web application.

    env-Web

    Outcomes

    IDTypeOutcome Description
    1Success
    A list of links is created by the attacker.

    Security Controls

    IDTypeSecurity Control Description
    1Detective
    Monitor velocity of page fetching in web logs. Humans who view a page and select a link from it will click far slower and far less regularly than tools. Tools make requests very quickly and the requests are typically spaced apart regularly (e.g. 0.8 seconds between them).
    2Detective
    Create links on some pages that are visually hidden from web browsers. Using iframes, images, or other HTML techniques, the links can be hidden from web browsing humans, but visible to spiders and programs. A request for the page, then, becomes a good predictor of an automated tool probing the application.
    3Preventative
    Actively monitor the application and either deny or redirect requests from origins that appear to be automated.
Experiment
  1. Attempt well-known or guessable resource locations:

    Using an automated tool, an attacker requests a variety of well-known URLs that correspond to administrative, debugging, or other useful internal actions. He records all the positive responses from the server.

    Attack Step Techniques

    IDAttack Step Technique DescriptionEnvironments
    1

    Use a spidering tool to follow and record attempts on well-known URLs

    env-Web
    2

    Use a proxy tool to record all links visited during a manual traversal of attempts on well-known URLs.

    env-Web

    Indicators

    IDTypeIndicator DescriptionEnvironments
    1Positive

    Common resource identifiers are used (e.g., /admin/, admin.jsp, admin.aspx, etc.)

    env-Web
    2Positive

    Well-known middleware or application platforms are used (e.g., Cold Fusion, WebSphere, WebLogic, JBoss, etc.)

    env-Web

    Outcomes

    IDTypeOutcome Description
    1Success
    The attacker discovers one or more unprotected resources.

    Security Controls

    IDTypeSecurity Control Description
    1Detective
    Monitor errors (e.g., 404 not found) from web servers, application servers, and other HTTP infrastructure (e.g., load balancers). Alert on an unusual number of consecutive failures or total failures from a single host. Potentially alert on many failures from many different hosts, but in a relatively short time window.
    2Detective
    Create "honeypot" web pages or scripts that do not actually have any use in the application, and name them common names (e.g., admin.jsp, admin.do, admin.aspx, etc.). Alert when one of these resources is requested.
    3Preventative
    Actively monitor the application and either deny or redirect requests from origins that appear to be generating an unusual amount of failures.
    4Corrective
    Obtain a list of sensitive areas that should not be directly accessible (e.g., JSPs or other templates that should only be accessible via front controllers). Apply an external mechanism (rule in the load balancer, rule in the reverse proxy, etc.) to intercept and redirect requests for those resources. Ideally use patterns, not specific page names (e.g., /jsp/* instead of a list of individual JSPs). Regularly update the list that is used in operation.
    5Detective
    Identify defaults for platform-specific sensitive resources. If the application does not use those defaults, alert on all requests for them (e.g., http://server:8080/admin/)
Exploit
  1. Use unauthorized resources:

    By visiting the unprotected resource, the attacker makes use of unauthorized functionality.

    Attack Step Techniques

    IDAttack Step Technique DescriptionEnvironments
    1

    Access unprotected functions and execute them.

    env-All

    Security Controls

    IDTypeSecurity Control Description
    1Detective
    Malformed log entries are a common side-effect of this kind of attack. E.g., "User xyz deleted by on 10/16/07." The "by on" indicates that no authorized user was recorded. (A good entry would say "user xyz deleted by admin on 10/16/07"). Monitoring of log file entries for correct and consistent output format can indicate this kind of attack succeeding.
  2. View unauthorized data:

    The attacker discovers and views unprotected sensitive data.

    Attack Step Techniques

    IDAttack Step Technique DescriptionEnvironments
    1

    Direct request of protected pages that directly access database back-ends. (e.g., list.jsp, accounts.jsp, status.jsp, etc.)

    env-Web

    Indicators

    IDTypeIndicator DescriptionEnvironments
    1Positive

    Dynamic pages (JSP, ASP, PHP, etc.) exist that divulge sensitive data without first checking authorization.

    env-Web
+ Attack Prerequisites
  • The forcibly browseable pages or accessible resources must be discoverable and improperly protected.

+ Typical Severity

High

+ Typical Likelihood of Exploit

Likelihood: Very High

A number of automated crawlers as well as other tools are available that generally perform a good job at looking for forcefully browseable pages

+ Methods of Attack
  • Brute Force
+ Examples-Instances

Description

A bulletin board application provides an administrative interface at admin.aspx when the user logging in belongs to the administrators group.

An attacker can access the admin.aspx interface by making a direct request to the page. Not having access to the interface appropriately protected allows the attacker to perform administrative functions without having to authenticate himself in that role.

+ Attacker Skills or Knowledge Required

Skill or Knowledge Level: Low

Forcibly browseable pages can be discovered by using a number of automated tools. Doing the same manually is tedious but by no means difficult

+ Resources Required

A directory listing is helpful but not a requirement. No special resources are required.

+ Probing Techniques

Following all the links recursively reveals resources that are available

Having a directory listing also points to the available pages and resources in the application that may be forcibly browseable.

+ Solutions and Mitigations

Authenticate request to every resource. In addition, every page or resource must ensure that the request it is handling has been made in an authorized context.

Forceful browsing can also be made difficult to a large extent by not hard-coding names of application pages or resources. This way, the attacker cannot figure out, from the application alone, the resources available from the present context.

+ Attack Motivation-Consequences
ScopeTechnical ImpactNote
Confidentiality
Read files or directories
Confidentiality
Access_Control
Authorization
Bypass protection mechanism
+ Content History
Submissions
SubmitterOrganizationDateSource
CAPEC Content TeamThe MITRE Corporation2014-06-23Internal_CAPEC_Team
Modifications
ModifierOrganizationDateCommentsSource
CAPEC Content TeamThe MITRE Corporation2015-12-07Updated Related_Attack_PatternsInternal
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Page Last Updated or Reviewed: May 01, 2017