CWE

Common Weakness Enumeration

A Community-Developed List of Software Weakness Types

CWE/SANS Top 25 Most Dangerous Software Errors
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ID

CWE-644: Improper Neutralization of HTTP Headers for Scripting Syntax

Weakness ID: 644
Abstraction: Variant
Structure: Simple
Status: Incomplete
Presentation Filter:
+ Description
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.

+ Relationships

The table(s) below shows the weaknesses and high level categories that are related to this weakness. 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 PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.

+ Relevant to the view "Research Concepts" (CWE-1000)
NatureTypeIDName
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More general than a Base weakness.116Improper Encoding or Escaping of Output
+ Relevant to the view "Development Concepts" (CWE-699)
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.442Web Problems
ChildOfClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More general than a Base weakness.116Improper Encoding or Escaping of Output
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.

PhaseNote
Architecture and Design
Implementation
+ Applicable Platforms
The listings below show possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

Class: Language-Independent (Undetermined Prevalence)

+ Common Consequences

The table below specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. 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 weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.

ScopeImpactLikelihood
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
+ 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.

(bad code)
Example Language: Java 
response.addHeader(HEADER_NAME, untrustedRawInputData);
+ Observed Examples
ReferenceDescription
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

Phase: Architecture and Design

Perform output validation in order to filter/escape/encode unsafe data that is being passed from the server in an HTTP response header.

Phase: Architecture and Design

Disable script execution functionality in the clients' browser.
+ Memberships
This MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.725OWASP Top Ten 2004 Category A4 - Cross-Site Scripting (XSS) Flaws
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.990SFP Secondary Cluster: Tainted Input to Command
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
Software Fault PatternsSFP24Tainted input to command
+ Content History
Submissions
Submission DateSubmitterOrganization
2008-01-30Evgeny LebanidzeCigital
Modifications
Modification DateModifierOrganization
2008-07-01Sean EidemillerCigital
added/updated demonstrative examples
2008-09-08CWE Content TeamMITRE
updated Common_Consequences, Relationships, Observed_Example
2008-10-14CWE Content TeamMITRE
updated Description, Name, Observed_Examples, Relationships
2009-03-10CWE Content TeamMITRE
updated Relationships
2009-05-27CWE Content TeamMITRE
updated Description, Name
2009-10-29CWE Content TeamMITRE
updated Common_Consequences
2010-04-05CWE Content TeamMITRE
updated Description, Name
2010-06-21CWE Content TeamMITRE
updated Demonstrative_Examples, Description, Observed_Examples
2010-12-13CWE Content TeamMITRE
updated Common_Consequences
2011-03-29CWE Content TeamMITRE
updated Description
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2012-05-11CWE Content TeamMITRE
updated Relationships
2012-10-30CWE Content TeamMITRE
updated Potential_Mitigations
2014-07-30CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Enabling_Factors_for_Exploitation
Previous Entry Names
Change DatePrevious Entry Name
2008-10-14Insufficient Filtering of HTTP Headers for Scripting Syntax
2009-05-27Insufficient Sanitization of HTTP Headers for Scripting Syntax
2010-04-05Improper Sanitization of HTTP Headers for Scripting Syntax

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Page Last Updated: March 29, 2018