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Common Weakness Enumeration

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ID

CWE-293: Using Referer Field for Authentication

Weakness ID: 293
Vulnerability Mapping: ALLOWEDThis CWE ID may be used to map to real-world vulnerabilities
Abstraction: VariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.
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+ Description
The referer field in HTTP requests can be easily modified and, as such, is not a valid means of message integrity checking.
+ Alternate Terms
referrer:
While the proper spelling might be regarded as "referrer," the HTTP RFCs and their implementations use "referer," so this is regarded as the correct spelling.
+ Relationships
Section HelpThis table 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
ChildOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.290Authentication Bypass by Spoofing
Section HelpThis table 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 "Architectural Concepts" (CWE-1008)
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1010Authenticate Actors
+ Background Details
The referer field in HTML requests can be simply modified by malicious users, rendering it useless as a means of checking the validity of the request in question.
+ Modes Of Introduction
Section HelpThe different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.
PhaseNote
Architecture and DesignCOMMISSION: This weakness refers to an incorrect design related to an architectural security tactic.
+ Applicable Platforms
Section HelpThis listing shows 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: Not Language-Specific (Undetermined Prevalence)

+ Common Consequences
Section HelpThis table 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
Access Control

Technical Impact: Gain Privileges or Assume Identity

Actions, which may not be authorized otherwise, can be carried out as if they were validated by the server referred to.
+ Likelihood Of Exploit
High
+ Demonstrative Examples

Example 1

The following code samples check a packet's referer in order to decide whether or not an inbound request is from a trusted host.

(bad code)
Example Language: C++ 
String trustedReferer = "http://www.example.com/"
while(true){
n = read(newsock, buffer, BUFSIZE);
requestPacket = processPacket(buffer, n);
if (requestPacket.referer == trustedReferer){
openNewSecureSession(requestPacket);
}
}
(bad code)
Example Language: Java 
boolean processConnectionRequest(HttpServletRequest request){
String referer = request.getHeader("referer")
String trustedReferer = "http://www.example.com/"
if(referer.equals(trustedReferer)){
openPrivilegedConnection(request);
return true;
}
else{
sendPrivilegeError(request);
return false;
}
}

These examples check if a request is from a trusted referer before responding to a request, but the code only verifies the referer name as stored in the request packet. An attacker can spoof the referer, thus impersonating a trusted client.

+ Potential Mitigations

Phase: Architecture and Design

In order to usefully check if a given action is authorized, some means of strong authentication and method protection must be used. Use other means of authorization that cannot be simply spoofed. Possibilities include a username/password or certificate.
+ Detection Methods

Automated Static Analysis

Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)

Effectiveness: High

+ Memberships
Section HelpThis 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.949SFP Secondary Cluster: Faulty Endpoint Authentication
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1396Comprehensive Categorization: Access Control
+ Vulnerability Mapping Notes

Usage: ALLOWED

(this CWE ID could be used to map to real-world vulnerabilities)

Reason: Acceptable-Use

Rationale:

This CWE entry is at the Variant level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.

Comments:

Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
CLASPUsing referrer field for authentication
Software Fault PatternsSFP29Faulty endpoint authentication
+ References
[REF-62] Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 17, "Referer Request Header", Page 1030. 1st Edition. Addison Wesley. 2006.
[REF-18] Secure Software, Inc.. "The CLASP Application Security Process". 2005. <https://cwe.mitre.org/documents/sources/TheCLASPApplicationSecurityProcess.pdf>.
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2006-07-19
(CWE Draft 3, 2006-07-19)
CLASP
+ Modifications
Modification DateModifierOrganization
2008-09-08CWE Content TeamMITRE
updated Alternate_Terms, Background_Details, Common_Consequences, Relationships, Relevant_Properties, Taxonomy_Mappings
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2012-05-11CWE Content TeamMITRE
updated Common_Consequences, Demonstrative_Examples, References, Relationships
2012-10-30CWE Content TeamMITRE
updated Demonstrative_Examples
2014-07-30CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Modes_of_Introduction, Relationships, Relevant_Properties
2020-02-24CWE Content TeamMITRE
updated Relationships
2021-03-15CWE Content TeamMITRE
updated References
2023-04-27CWE Content TeamMITRE
updated Detection_Factors, Relationships
2023-06-29CWE Content TeamMITRE
updated Mapping_Notes
Page Last Updated: February 29, 2024