CAPEC-209: XSS Using MIME Type Mismatch

Description

An adversary creates a file with scripting content but where the specified MIME type of the file is such that scripting is not expected. The adversary tricks the victim into accessing a URL that responds with the script file. Some browsers will detect that the specified MIME type of the file does not match the actual type of its content and will automatically switch to using an interpreter for the real content type. If the browser does not invoke script filters before doing this, the adversary's script may run on the target unsanitized, possibly revealing the victim's cookies or executing arbitrary script in their browser.

Extended Description

Adversaries can, in some cases, get around logic put in place to 'guard' sensitive functionality or data. Client applications may include functionality that a server relies on for correct and secure operation. This functionality can include, but is not limited to, filters to prevent the sending of dangerous content to the server, logical functionality such as price calculations, and authentication logic to ensure that only authorized users are utilizing the client. If an adversary can disable this functionality on the client, they can perform actions that the server believes are prohibited. This can result in client behavior that violates assumptions by the server leading to a variety of possible attacks. In the above examples, this could include the sending of dangerous content (such as scripts) to the server, incorrect price calculations, or unauthorized access to server resources.

Severity :

Medium

Possibility :

Type :

Detailed

Relationships with other CAPECs

This table shows the other attack patterns and high level categories that are related to this attack pattern.

CAPEC-592: Stored XSS Stored XSS

Prerequisites

This table shows the other attack patterns and high level categories that are related to this attack pattern.

The victim must follow a crafted link that references a scripting file that is mis-typed as a non-executable file.
The victim's browser must detect the true type of a mis-labeled scripting file and invoke the appropriate script interpreter without first performing filtering on the content.

Skills required

This table shows the other attack patterns and high level categories that are related to this attack pattern.

Taxonomy mappings

Mappings to ATT&CK, OWASP and other frameworks.

Resources required

The adversary must have the ability to source the file of the incorrect MIME type containing a script.

Related CWE

A Related Weakness relationship associates a weakness with this attack pattern. Each association implies a weakness that must exist for a given attack to be successful.

CWE-20: Improper Input Validation

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CWE-646: Reliance on File Name or Extension of Externally-Supplied File

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