Forceful Browsing |
| Attack Pattern ID: 87 (Standard Attack Pattern Completeness: Complete) | Typical Severity: High | Status: Draft |
DescriptionSummary
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 appplication that have been improperly protected.
Attack Execution Flow
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-Web2 Use a proxy tool to record all links visited during a manual traversal of the web application.
env-WebOutcomes
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.
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-Web2 Use a proxy tool to record all links visited during a manual traversal of attempts on well known URLs.
env-WebIndicators
ID type Indicator Description Environments 1 Positive Common resource identifiers are used (e.g., /admin/, admin.jsp, admin.aspx, etc.)
env-Web2 Positive Well known middleware or application platforms are used (e.g., Cold Fusion, WebSphere, WebLogic, JBoss, etc.)
env-WebOutcomes
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/)
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-AllSecurity 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.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-WebIndicators
ID type Indicator Description Environments 1 Positive Dynamic pages (JSP, ASP, PHP, etc.) exist that divulge sensitive data without first checking authorization.
env-Web
Attack PrerequisitesThe forcibly browsable pages or accessible resources must be discoverable and improperly protected.
Typical Likelihood of ExploitLikelihood: 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
Methods of Attack- Brute Force
Examples-InstancesDescription
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 admnistrative functions without having to authenticate himself in that role.
Attacker Skills or Knowledge RequiredSkill 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
Resources RequiredA directory listing is helpful but not a requirement. No special resources are required.
Probing TechniquesFollowing 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.
Solutions and MitigationsAuthenticate 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- Information Leakage
- Privilege Escalation
Related Weaknesses Related Vulnerabilities| Vulnerability ID | Relationship Description |
|---|---|
| CVE-2007-1156 | JBrowser allows remote attackers to bypass authentication and access certain administrative capabilities via a direct request for _admin/. |
| CVE-2007-1062 | The Cisco Unified IP Conference Station 7935 3.2(15) and earlier, and Station 7936 3.3(12) and earlier does not properly handle administrator HTTP sessions, which allows remote attackers to bypass authentication controls via a direct URL request to the administrative HTTP interface for a limited time |
Related Attack Patterns| Nature | Type | ID | Name | Description | View(s) this relationship pertains to |
|---|---|---|---|---|---|
| ChildOf |  Category | 210 | Abuse of Functionality | Mechanism of Attack (primary)1000 | |
| ChildOf | Category | 367 | WASC Threat Classification 2.0 - WASC-34 - Predictable Resource Location | WASC Threat Classification 2.0333 | |
| ParentOf |  Attack Pattern | 143 | Detect Unpublicised Web Pages | Mechanism of Attack (primary)1000 | |
| ParentOf | Attack Pattern | 144 | Detect Unpublicised Web Services | Mechanism of Attack (primary)1000 |
Related Security PrinciplesComplete Mediation
Reluctance To Trust
Related GuidelinesTreat the Entire Inherited Process Context as Unvalidated Input
Use Authentication Mechanisms, Where Appropriate, Correctly
Content History| Submissions | ||||
|---|---|---|---|---|
| Submitter | Date | Comments | ||
| Chiradeep B. Chhaya | 2007-03-13 | First Draft | ||
| Modifications | |||||
|---|---|---|---|---|---|
| Modifier | Organization | Date | Comments | ||
| Sean Barnum | Cigital, Inc | 2007-04-16 | Review and revise | ||
| Paco Hope | Cigital, Inc. | 2007-10-20 | Added extended Attack Execution Flow | ||
