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ID

CWE-293: Using Referer Field for Authentication

Weakness ID: 293
Abstraction: Variant
Structure: Simple
Status: Draft
Presentation Filter:
+ 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

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
ChildOfBaseBase - a weakness that is described in an abstract fashion, but with sufficient details to infer specific methods for detection and prevention. More general than a Variant weakness, but more specific than a Class weakness.290Authentication Bypass by Spoofing
+ 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
+ Relevant to the view "Development Concepts" (CWE-699)
NatureTypeIDName
ChildOfBaseBase - a weakness that is described in an abstract fashion, but with sufficient details to infer specific methods for detection and prevention. More general than a Variant weakness, but more specific than a Class weakness.290Authentication Bypass by Spoofing
+ 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

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 DesignCOMMISSION: This weakness refers to an incorrect design related to an architectural security tactic.
+ 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
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.
+ 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.949SFP Secondary Cluster: Faulty Endpoint Authentication
+ 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.
+ Content History
Submissions
Submission DateSubmitterOrganization
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

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Page Last Updated: March 29, 2018