CWE-644: Improper Sanitization of HTTP Headers for Scripting Syntax
Improper Sanitization of HTTP Headers for Scripting Syntax
Weakness ID: 644 (Weakness Variant)
Status: Incomplete
Description
Description Summary
The application does not sanitize or incorrectly sanitizes web
scripting syntax in HTTP headers that can be used by web browser components that
can process raw headers, such as Flash.
Extended Description
If an application fails to filter or escape user controlled data being
placed in the header of an HTTP response coming from the server, the header
may contain a script that will get executed in the client's browser context,
potentially resulting in a cross site scripting vulnerability or possibly an
HTTP response splitting attack. It is important to carefully control data
that is being placed both in HTTP response header and in the HTTP response
body to ensure that no scripting syntax is present, taking various encodings
into account.
Time of Introduction
Architecture and Design
Implementation
Applicable Platforms
Languages
All
Common Consequences
Scope
Effect
Integrity
Run Arbitrary Code
Confidentiality
Information Leakage
Likelihood of Exploit
High
Enabling Factors for Exploitation
Script execution functionality is enabled in the user's browser.
Demonstrative Examples
Example 1
In the following Java example, user-controlled data is added to the
HTTP headers and returned to the client. Given that the data is not subject
to sanitization, a malicious user may be able to inject dangerous scripting
tags that will lead to script execution in the client browser.
Web server does not sanitize the Expect header
from an HTTP request when it is reflected back in an error message, allowing
a Flash SWF file to perform XSS attacks.
Potential Mitigations
Phase
Description
Perform output validation in order to filter/escape/encode unsafe data
that is being passed from the server in an HTTP response header.
Disable script execution functionality in the clients' browser.
Description
