CWE-644: Improper Neutralization of HTTP Headers for Scripting Syntax
Improper Neutralization of HTTP Headers for Scripting Syntax
Weakness ID: 644 (Weakness Variant)
Status: Incomplete
Description
Description Summary
The application does not neutralize or incorrectly neutralizes web scripting syntax in HTTP headers that can be used by web browser components that can process raw headers, such as Flash.
Extended Description
An attacker may be able to conduct cross-site scripting and other attacks against users who have these components enabled.
If an application does not neutralize 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
Confidentiality
Availability
Technical Impact: Execute unauthorized code or
commands
Run arbitrary code.
Confidentiality
Technical Impact: Read application
data
Attackers may be able to obtain sensitive information.
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 neutralization, 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 remove 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
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
