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CAPEC-86: XSS Through HTTP Headers

Attack Pattern ID: 86
Abstraction: Detailed
Status: Draft
Presentation Filter:
+ Description
An adversary exploits web applications that generate web content, such as links in a HTML page, based on unvalidated or improperly validated data submitted by other actors. XSS in HTTP Headers attacks target the HTTP headers which are hidden from most users and may not be validated by web applications.
+ Likelihood Of Attack

High

+ Typical Severity

Very High

+ Relationships

The table(s) below shows the other attack patterns and high level categories that are related to this attack pattern. These relationships are defined as ChildOf, ParentOf, MemberOf 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.

+ Relevant to the view "Mechanisms of Attack" (CAPEC-1000)
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
+ Execution Flow
Explore
  1. Spider: Using a browser or an automated tool, an attacker follows all public links on a web site. He records all the entry points (input) that becomes part of generated HTTP header (not only GET/POST/COOKIE, but also Content-Type, etc.) Use a spidering tool to follow and record all links and analyze the web pages to find entry points. Make special note of any links that include parameters used in the HTTP headers. Look for HTML meta tags that could be injectable Use a proxy tool to record all links visited during a manual traversal of the web application. Use a browser to manually explore the website and analyze how it is constructed. Many browsers' plugins are available to facilitate the analysis or automate the discovery.

    Techniques
    Use a spidering tool to follow and record all links and analyze the web pages to find entry points. Make special note of any links that include parameters used in the HTTP headers.
    Look for HTML meta tags that could be injectable
    Use a proxy tool to record all links visited during a manual traversal of the web application.
    Use a browser to manually explore the website and analyze how it is constructed. Many browsers' plugins are available to facilitate the analysis or automate the discovery.
Experiment
  1. Probe identified potential entry points for XSS vulnerability:

    Techniques
    Manually inject various script payloads into each identified entry point using a list of common script injection probes and observe system behavior to determine if script was executed.
    Use an automated injection attack tool to inject various script payloads into each identified entry point using a list of common script injection probes and observe system behavior to determine if script was executed.
    Use a proxy tool to record results of manual input of XSS probes in known URLs.
Exploit
  1. Steal session IDs, credentials, page content, etc.: As the attacker succeeds in exploiting the vulnerability, he can choose to steal user's credentials in order to reuse or to analyze them later on. Develop malicious JavaScript that is injected through vectors identified during the Experiment Phase and loaded by the victim's browser and sends document information to the attacker. Develop malicious JavaScript that injected through vectors identified during the Experiment Phase and takes commands from an attacker's server and then causes the browser to execute appropriately.

    Techniques
    Develop malicious JavaScript that is injected through vectors identified during the Experiment Phase and loaded by the victim's browser and sends document information to the attacker.
    Develop malicious JavaScript that injected through vectors identified during the Experiment Phase and takes commands from an attacker's server and then causes the browser to execute appropriately.
  2. Forceful browsing: When the attacker targets the current application or another one (through CSRF vulnerabilities), the user will then be the one who perform the attacks without being aware of it. These attacks are mostly targeting application logic flaws, but it can also be used to create a widespread attack against a particular website on the user's current network (Internet or not). Develop malicious JavaScript that is injected through vectors identified during the Experiment Phase and loaded by the victim's browser and performs actions on the same web site Develop malicious JavaScript that injected through vectors identified during the Experiment Phase and takes commands from an attacker's server and then causes the browser to execute request to other web sites (especially the web applications that have CSRF vulnerabilities).

    Techniques
    Develop malicious JavaScript that is injected through vectors identified during the Experiment Phase and loaded by the victim's browser and performs actions on the same web site
    Develop malicious JavaScript that injected through vectors identified during the Experiment Phase and takes commands from an attacker's server and then causes the browser to execute request to other web sites (especially the web applications that have CSRF vulnerabilities).
  3. Content spoofing: By manipulating the content, the attacker targets the information that the user would like to get from the website. Develop malicious JavaScript that is injected through vectors identified during the Experiment Phase and loaded by the victim's browser and exposes attacker-modified invalid information to the user on the current web page.

    Techniques
    Develop malicious JavaScript that is injected through vectors identified during the Experiment Phase and loaded by the victim's browser and exposes attacker-modified invalid information to the user on the current web page.
+ Prerequisites
Target software must be a client that allows scripting communication from remote hosts.
+ Skills Required
[Level: Low]
To achieve a redirection and use of less trusted source, an attacker can simply edit HTTP Headers that are sent to client machine.
[Level: High]
Exploiting a client side vulnerability to inject malicious scripts into the browser's executable process.
+ Resources Required
The adversary must have the ability to deploy a custom hostile service for access by targeted clients and the abbility to communicate synchronously or asynchronously with client machine. The adversary must also control a remote site of some sort to redirect client and data to.
+ Consequences

The table below 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
Integrity
Availability
Execute Unauthorized Commands
Confidentiality
Read Data
Confidentiality
Access Control
Authorization
Gain Privileges
+ 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.
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.
+ Example Instances

Utilize a remote style sheet set in the HTTP header for XSS attack. When the attacker is able to point to a remote stylesheet, any of the variables set in that stylesheet are controllable on the client side by the remote attacker. Like most XSS attacks, results vary depending on browser that is used.

<META HTTP-EQUIV="Link" Content="<http://ha.ckers.org/xss.css>; REL=stylesheet">

[R.86.2]

Google's 404 redirection script was found vulnerable to this attack vector.

Google's 404 file not found page read

* Response headers: "Content-Type: text/html; charset=[encoding]".

* Response body: <META http-equiv="Content-Type" (...) charset=[encoding]/>

If the response sends an unexpected encoding type such as UTF-7, then no enforcement is done on the payload and arbitrary XSS code will be transported along with the standard HTTP response. [R.86.3]

XSS can be used in variety of ways, because it is scripted and executes in a distributed, asynchronous fashion it can create its own vector and openings. For example, the attacker can use XSS to mount a DDoS attack by having series of different computers unknowingly executing requests against a single host.
+ References
[REF-1] G. Hoglund and G. McGraw. "Exploiting Software: How to Break Code". Addison-Wesley. 2004-02.
[REF-97] "OWASP Cheatsheets". XSS Filter Evasion Cheat Sheet. The Open Web Application Security Project (OWASP). <http://ha.ckers.org/xss.html>.
[REF-476] Watchfire Research. "XSS vulnerabilities in Google.com". Full Disclosure mailing list archives. <http://seclists.org/fulldisclosure/2005/Dec/1107>.
+ Content History
Submissions
Submission DateSubmitterOrganization
2014-06-23CAPEC Content TeamThe MITRE Corporation
Modifications
Modification DateModifierOrganization
2017-05-01CAPEC Content TeamThe MITRE Corporation
Updated Attack_Prerequisites, Description Summary, Related_Attack_Patterns, Related_Weaknesses, Resources_Required
Previous Entry Names
Change DatePrevious Entry Name
2017-05-01Embedding Script (XSS) in HTTP Headers

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Page Last Updated or Reviewed: July 31, 2018