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CAPEC-32: XSS Through HTTP Query Strings

Attack Pattern ID: 32
Abstraction: Detailed
Status: Draft
Presentation Filter:
+ Description
An adversary embeds malicious script code in the parameters of an HTTP query string and convinces a victim to submit the HTTP request that contains the query string to a vulnerable web application. The web application then procedes to use the values parameters without properly validation them first and generates the HTML code that will be executed by the victim's browser.
+ Likelihood Of Attack

High

+ Typical Severity

High

+ Relationships
Section HelpThis table shows the other attack patterns and high level categories that are related to this attack pattern. These relationships are defined as ChildOf and ParentOf, and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as CanFollow, PeerOf, and CanAlsoBe are defined to show similar attack patterns that the user may want to explore.
NatureTypeIDName
ChildOfDetailed Attack PatternDetailed Attack Pattern - A detailed level attack pattern in CAPEC provides a low level of detail, typically leveraging a specific technique and targeting a specific technology, and expresses a complete execution flow. Detailed attack patterns are more specific than meta attack patterns and standard attack patterns and often require a specific protection mechanism to mitigate actual attacks. A detailed level attack pattern often will leverage a number of different standard level attack patterns chained together to accomplish a goal.588DOM-Based XSS
ChildOfDetailed Attack PatternDetailed Attack Pattern - A detailed level attack pattern in CAPEC provides a low level of detail, typically leveraging a specific technique and targeting a specific technology, and expresses a complete execution flow. Detailed attack patterns are more specific than meta attack patterns and standard attack patterns and often require a specific protection mechanism to mitigate actual attacks. A detailed level attack pattern often will leverage a number of different standard level attack patterns chained together to accomplish a goal.591Reflected XSS
ChildOfDetailed Attack PatternDetailed Attack Pattern - A detailed level attack pattern in CAPEC provides a low level of detail, typically leveraging a specific technique and targeting a specific technology, and expresses a complete execution flow. Detailed attack patterns are more specific than meta attack patterns and standard attack patterns and often require a specific protection mechanism to mitigate actual attacks. A detailed level attack pattern often will leverage a number of different standard level attack patterns chained together to accomplish a goal.592Stored XSS
Section HelpThis table shows the views that this attack pattern belongs to and top level categories within that view.
+ Execution Flow
Explore
  1. Survey the application for public links: Using a browser or an automated tool, an adversary follows all public links on a web site. They record all the links they find.

    Techniques
    Use a spidering tool to follow and record all links. Make special note of any links that include parameters in the URL.
    Use a proxy tool to record all links visited during a manual traversal of the web application. Make special note of any links that include parameters in the URL. Manual traversal of this type is frequently necessary to identify forms that are GET method forms rather than POST forms.
    Use a browser to manually explore the website and analyze how it is constructed. Many browser's plugins are available to facilitate the analysis or automate the URL discovery.
Experiment
  1. Probe public links for XSS vulnerability: The adversary uses the public links gathered in the "Explore" phase as a target list and requests variations on the URLs they spidered before. They send parameters that include variations of payloads. They record all the responses from the server that include unmodified versions of their script.

    Techniques
    Use a list of XSS probe strings to inject in parameters of known URLs. If possible, the probe strings contain a unique identifier.
    Use a proxy tool to record results of manual input of XSS probes in known URLs.
  2. Craft malicious XSS URL: Once the adversary has determined which parameters are vulnerable to XSS, they will craft a malicious URL containing the XSS exploit. The adversary can have many goals, from stealing session IDs, cookies, credentials, and page content from the victim.

    Techniques
    Change a URL parameter to include a malicious script tag.
    Send information gathered from the malicious script to a remote endpoint.
Exploit
  1. Get victim to click URL: In order for the attack to be successful, the victim needs to access the malicious URL.

    Techniques
    Send a phishing email to the victim containing the malicious URL. This can be hidden in a hyperlink as to not show the full URL, which might draw suspicion.
    Put the malicious URL on a public forum, where many victims might accidentally click the link.
+ Prerequisites
Target client software must allow scripting such as JavaScript. Server software must allow display of remote generated HTML without sufficient input or output validation.
+ Skills Required
[Level: Low]
To place malicious payload on server via HTTP
[Level: High]
Exploiting any information gathered by HTTP Query on script host
+ Resources Required
Ability to send HTTP post to scripting host and collect output
+ Consequences
Section HelpThis table specifies different individual consequences associated with the attack pattern. The Scope identifies the security property that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in their attack. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a pattern will be used to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
ScopeImpactLikelihood
Confidentiality
Read Data
Confidentiality
Integrity
Availability
Execute Unauthorized Commands
+ Mitigations
Design: Use browser technologies that do not allow client side scripting.
Design: Utilize strict type, character, and encoding enforcement
Design: Server side developers should not proxy content via XHR or other means, if a http proxy for remote content is setup on the server side, the client's browser has no way of discerning where the data is originating from.
Implementation: Ensure all content that is delivered to client is sanitized against an acceptable content specification.
Implementation: Perform input validation for all remote content, including remote and user-generated content
Implementation: Perform output validation for all remote content.
Implementation: Disable scripting languages such as JavaScript in browser
Implementation: Session tokens for specific host
Implementation: Patching software. There are many attack vectors for XSS on the client side and the server side. Many vulnerabilities are fixed in service packs for browser, web servers, and plug in technologies, staying current on patch release that deal with XSS countermeasures mitigates this.
Implementation: Privileges are constrained, if a script is loaded, ensure system runs in chroot jail or other limited authority mode
+ Example Instances
http://user:host@example.com:8080/oradb<script>alert('Hi')</script>

Web applications that accept name value pairs in a HTTP Query string are inherently at risk to any value (or name for that matter) that an adversary would like to enter in the query string. This can be done manually via web browser or trivially scripted to post the query string to multiple sites. In the latter case, in the instance of many sites using similar infrastructure with predictable http queries being accepted and operated on (such as blogging software, Google applications, and so on), a single malicious payload can be scripted to target a wide variety of sites.

Web 2.0 type sites like Technorati and del.icio.us rely on user generated content like tags to build http links that are displayed to other users. del.icio.us allows users to identify sites, tag them with metadata and provide URL, descriptions and more data. This data is then echoed back to any other web browser that is interested in the link. If the data is not validated by the del.icio.us site properly then an arbitrary code can be added into the standard http string sent to del.icio.us by the adversary, for example formatted as normal content with a URL and description and tagged as Java, and available to be clicked on (and executed by) any user browsing for Java content that clicks on this trojaned content.

+ References
[REF-1] G. Hoglund and G. McGraw. "Exploiting Software: How to Break Code". Addison-Wesley. 2004-02.
+ Content History
Submissions
Submission DateSubmitterOrganization
2014-06-23CAPEC Content TeamThe MITRE Corporation
Modifications
Modification DateModifierOrganization
2015-11-09CAPEC Content TeamThe MITRE Corporation
Updated Attack_Phases
2015-12-07CAPEC Content TeamThe MITRE Corporation
Updated Attack_Phases
2017-01-09CAPEC Content TeamThe MITRE Corporation
Updated Attack_Phases
2017-05-01CAPEC Content TeamThe MITRE Corporation
Updated Attack_Phases, Description Summary, Related_Attack_Patterns, Related_Weaknesses
2017-08-04CAPEC Content TeamThe MITRE Corporation
Updated Attack_Phases
2018-07-31CAPEC Content TeamThe MITRE Corporation
Updated Attack_Phases
2020-07-30CAPEC Content TeamThe MITRE Corporation
Updated Execution_Flow
2020-12-17CAPEC Content TeamThe MITRE Corporation
Updated Related_Attack_Patterns
2022-02-22CAPEC Content TeamThe MITRE Corporation
Updated Example_Instances, Execution_Flow
Previous Entry Names
Change DatePrevious Entry Name
2017-05-01Embedding Scripts in HTTP Query Strings
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Page Last Updated or Reviewed: October 21, 2021