Summary

Attack Execution Flow

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

   ID	Attack Step Technique Description	Environments
   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

   ID	type	Outcome Description
   1	Success	A list of links is created by the attacker.

   Security Controls

   ID	type	Security Control Description
   1	Detective	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).
   2	Detective	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.
   3	Preventative	Actively monitor the application and either deny or redirect requests from origins that appear to be automated.

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

   ID	Attack Step Technique Description	Environments
   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

   ID	type	Indicator Description	Environments
   1	Positive	Common resource identifiers are used (e.g., /admin/, admin.jsp, admin.aspx, etc.)	env-Web
   2	Positive	Well known middleware or application platforms are used (e.g., Cold Fusion, WebSphere, WebLogic, JBoss, etc.)	env-Web

   Outcomes

   ID	type	Outcome Description
   1	Success	The attacker discovers one or more unprotected resources.

   Security Controls

   ID	type	Security Control Description
   1	Detective	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.
   2	Detective	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.
   3	Preventative	Actively monitor the application and either deny or redirect requests from origins that appear to be generating an unusual amount of failures.
   4	Corrective	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.
   5	Detective	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/)

1. Use unauthorized resources:

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

   Attack Step Techniques

   ID	Attack Step Technique Description	Environments
   1	Access unprotected functions and execute them.	env-All

   Security Controls

   ID	type	Security Control Description
   1	Detective	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

   ID	Attack Step Technique Description	Environments
   1	Direct request of protected pages that directly access database back-ends. (e.g., list.jsp, accounts.jsp, status.jsp, etc.)	env-Web

   Indicators

   ID	type	Indicator Description	Environments
   1	Positive	Dynamic pages (JSP, ASP, PHP, etc.) exist that divulge sensitive data without first checking authorization.	env-Web

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 browsable pages

Description

Skill or Knowledge Level: Low

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

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 browsable.

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.