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Common Weakness Enumeration

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Home > CWE List > CWE-923: Improper Restriction of Communication Channel to Intended Endpoints (4.18)
ID
CWE Glossary Definition

CWE-923: Improper Restriction of Communication Channel to Intended Endpoints

Weakness ID: 923
Vulnerability Mapping: ALLOWED This CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review (with careful review of mapping notes)
Abstraction: Class Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.
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Description
The product establishes a communication channel to (or from) an endpoint for privileged or protected operations, but it does not properly ensure that it is communicating with the correct endpoint.
Extended Description

Attackers might be able to spoof the intended endpoint from a different system or process, thus gaining the same level of access as the intended endpoint.

While this issue frequently involves authentication between network-based clients and servers, other types of communication channels and endpoints can have this weakness.

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.
Impact Details

Gain Privileges or Assume Identity

Scope: Integrity, Confidentiality

If an attacker can spoof the endpoint, the attacker gains all the privileges that were intended for the original endpoint.
Relationships
Section Help This 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" (View-1000)
Nature Type ID Name
ChildOf Pillar Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things. 284 Improper Access Control
ParentOf Variant Variant - 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. 291 Reliance on IP Address for Authentication
ParentOf Variant Variant - 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. 297 Improper Validation of Certificate with Host Mismatch
ParentOf Class Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource. 300 Channel Accessible by Non-Endpoint
ParentOf Base Base - 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. 419 Unprotected Primary Channel
ParentOf Base Base - 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. 420 Unprotected Alternate Channel
ParentOf Base Base - 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. 940 Improper Verification of Source of a Communication Channel
ParentOf Base Base - 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. 941 Incorrectly Specified Destination in a Communication Channel
ParentOf Variant Variant - 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. 942 Permissive Cross-domain Security Policy with Untrusted Domains
ParentOf Variant Variant - 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. 1275 Sensitive Cookie with Improper SameSite Attribute
CanFollow Base Base - 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. 322 Key Exchange without Entity Authentication
CanFollow Variant Variant - 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. 350 Reliance on Reverse DNS Resolution for a Security-Critical Action
Relevant to the view "Architectural Concepts" (View-1008)
Nature Type ID Name
MemberOf Category Category - a CWE entry that contains a set of other entries that share a common characteristic. 1011 Authorize Actors
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.
Phase Note
Architecture and Design REALIZATION: This weakness is caused during implementation of 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)

Demonstrative Examples

Example 1


These cross-domain policy files mean to allow Flash and Silverlight applications hosted on other domains to access its data:

Flash crossdomain.xml :

(bad code)
Example Language: XML
<cross-domain-policy xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="http://www.adobe.com/xml/schemas/PolicyFile.xsd">
<allow-access-from domain="*.example.com"/>
<allow-access-from domain="*"/>
</cross-domain-policy>

Silverlight clientaccesspolicy.xml :

(bad code)
Example Language: XML
<?xml version="1.0" encoding="utf-8"?>
<access-policy>
<cross-domain-access>
<policy>
<allow-from http-request-headers="SOAPAction">
<domain uri="*"/>
</allow-from>
<grant-to>
<resource path="/" include-subpaths="true"/>
</grant-to>
</policy>
</cross-domain-access>
</access-policy>

These entries are far too permissive, allowing any Flash or Silverlight application to send requests. A malicious application hosted on any other web site will be able to send requests on behalf of any user tricked into executing it.



Example 2


This Android application will remove a user account when it receives an intent to do so:

(bad code)
Example Language: Java
IntentFilter filter = new IntentFilter("com.example.RemoveUser");
MyReceiver receiver = new MyReceiver();
registerReceiver(receiver, filter);

public class DeleteReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
int userID = intent.getIntExtra("userID");
destroyUserData(userID);
}
}

This application does not check the origin of the intent, thus allowing any malicious application to remove a user. Always check the origin of an intent, or create an allowlist of trusted applications using the manifest.xml file.



Selected Observed Examples

Note: this is a curated list of examples for users to understand the variety of ways in which this weakness can be introduced. It is not a complete list of all CVEs that are related to this CWE entry.

Reference Description
S-bus functionality in a home automation product performs access control using an IP allowlist, which can be bypassed by a forged IP address.
A troubleshooting tool exposes a web server on a random port between 9000-65535 that could be used for information gathering
A WAN interface on a router has firewall restrictions enabled for IPv4, but it does not for IPv6, which is enabled by default
Product has a Silverlight cross-domain policy that does not restrict access to another application, which allows remote attackers to bypass the Same Origin Policy.
Mobile banking application does not verify hostname, leading to financial loss.
chain: incorrect "goto" in Apple SSL product bypasses certificate validation, allowing Adversry-in-the-Middle (AITM) attack (Apple "goto fail" bug). CWE-705 (Incorrect Control Flow Scoping) -> CWE-561 (Dead Code) -> CWE-295 (Improper Certificate Validation) -> CWE-393 (Return of Wrong Status Code) -> CWE-300 (Channel Accessible by Non-Endpoint).
DNS server can accept DNS updates from hosts that it did not query, leading to cache poisoning
Detection Methods
Method Details

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.
Nature Type ID Name
MemberOf CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1396 Comprehensive Categorization: Access Control
Vulnerability Mapping Notes
Usage ALLOWED-WITH-REVIEW
(this CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review)
Reason Abstraction

Rationale

This CWE entry is a Class and might have Base-level children that would be more appropriate

Comments

Examine children of this entry to see if there is a better fit
Content History
Submissions
Submission Date Submitter Organization
2013年06月23日
(CWE 2.5, 2013年07月17日) 		CWE Content Team MITRE
Modifications
Modification Date Modifier Organization
2024年02月29日
(CWE 4.14, 2024年02月29日) 		CWE Content Team MITRE
updated Demonstrative_Examples
2023年10月26日 CWE Content Team MITRE
updated Observed_Examples
2023年06月29日 CWE Content Team MITRE
updated Mapping_Notes
2023年04月27日 CWE Content Team MITRE
updated Detection_Factors, Relationships
2023年01月31日 CWE Content Team MITRE
updated Description, Related_Attack_Patterns, Relationships
2022年10月13日 CWE Content Team MITRE
updated Related_Attack_Patterns, Relationships
2021年03月15日 CWE Content Team MITRE
updated Maintenance_Notes
2020年02月24日 CWE Content Team MITRE
updated Relationships
2019年01月03日 CWE Content Team MITRE
updated Related_Attack_Patterns
2017年11月08日 CWE Content Team MITRE
updated Modes_of_Introduction, Relationships
2014年02月18日 CWE Content Team MITRE
updated Description, Name, Relationships
Previous Entry Names
Change Date Previous Entry Name
2014年02月18日 Improper Authentication of Endpoint in a Communication Channel
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Page Last Updated: September 09, 2025

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