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Home > CWE List > CWE-940: Improper Verification of Source of a Communication Channel (4.16)  
ID

CWE-940: Improper Verification of Source of a Communication Channel

Weakness ID: 940
Vulnerability Mapping: ALLOWED This CWE ID may be used to map to real-world vulnerabilities
Abstraction: 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.
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+ Description
The product establishes a communication channel to handle an incoming request that has been initiated by an actor, but it does not properly verify that the request is coming from the expected origin.
+ Extended Description
When an attacker can successfully establish a communication channel from an untrusted origin, the attacker may be able to gain privileges and access unexpected functionality.
+ 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.
Scope Impact Likelihood
Access Control
Other

Technical Impact: Gain Privileges or Assume Identity; Varies by Context

An attacker can access any functionality that is inadvertently accessible to the source.
+ Potential Mitigations

Phase: Architecture and Design

Use a mechanism that can validate the identity of the source, such as a certificate, and validate the integrity of data to ensure that it cannot be modified in transit using an Adversary-in-the-Middle (AITM) attack.

When designing functionality of actions in the URL scheme, consider whether the action should be accessible to all mobile applications, or if an allowlist of applications to interface with is appropriate.
+ 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" (CWE-1000)
Nature Type ID Name
ChildOf 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. 346 Origin Validation Error
ChildOf 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. 923 Improper Restriction of Communication Channel to Intended Endpoints
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. 925 Improper Verification of Intent by Broadcast Receiver
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 "Software Development" (CWE-699)
Nature Type ID Name
MemberOf Category Category - a CWE entry that contains a set of other entries that share a common characteristic. 417 Communication Channel Errors
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 "Architectural Concepts" (CWE-1008)
Nature Type ID Name
MemberOf Category Category - a CWE entry that contains a set of other entries that share a common characteristic. 1014 Identify 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
Implementation 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)

Technologies

Class: Mobile (Undetermined Prevalence)

+ Demonstrative Examples

Example 1

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.


Example 2

These Android and iOS applications intercept URL loading within a WebView and perform special actions if a particular URL scheme is used, thus allowing the Javascript within the WebView to communicate with the application:

(bad code)
Example Language: Java 
// Android
@Override
public boolean shouldOverrideUrlLoading(WebView view, String url){
if (url.substring(0,14).equalsIgnoreCase("examplescheme:")){
if(url.substring(14,25).equalsIgnoreCase("getUserInfo")){
writeDataToView(view, UserData);
return false;
}
else{
return true;
}
}
}
(bad code)
Example Language: Objective-C 
// iOS
-(BOOL) webView:(UIWebView *)exWebView shouldStartLoadWithRequest:(NSURLRequest *)exRequest navigationType:(UIWebViewNavigationType)exNavigationType
{
NSURL *URL = [exRequest URL];
if ([[URL scheme] isEqualToString:@"exampleScheme"])
{
NSString *functionString = [URL resourceSpecifier];
if ([functionString hasPrefix:@"specialFunction"])
{

// Make data available back in webview.
UIWebView *webView = [self writeDataToView:[URL query]];
}
return NO;
}
return YES;
}

A call into native code can then be initiated by passing parameters within the URL:

(attack code)
Example Language: JavaScript 
window.location = examplescheme://method?parameter=value

Because the application does not check the source, a malicious website loaded within this WebView has the same access to the API as a trusted site.


+ Observed Examples
Reference Description
DNS server can accept DNS updates from hosts that it did not query, leading to cache poisoning
DNS server can accept DNS updates from hosts that it did not query, leading to cache poisoning
DNS server caches glue records received from non-delegated name servers
+ 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. 1353 OWASP Top Ten 2021 Category A07:2021 - Identification and Authentication Failures
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

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

Reason: Acceptable-Use

Rationale:

This CWE entry is at the Base 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.
+ Notes

Relationship

While many access control issues involve authenticating the user, this weakness is more about authenticating the actual source of the communication channel itself; there might not be any "user" in such cases.
+ References
[REF-324] Taimur Aslam. "A Taxonomy of Security Faults in the UNIX Operating System". 1995-08-01. <https://cwe.mitre.org/documents/sources/ATaxonomyofSecurityFaultsintheUNIXOperatingSystem%5BAslam95%5D.pdf>. URL validated: 2024-11-17.
+ Content History
+ Submissions
Submission Date Submitter Organization
2014-02-13
(CWE 2.6, 2014-02-19) 		CWE Content Team MITRE
+ Modifications
Modification Date Modifier Organization
2017-11-08 CWE Content Team MITRE
updated Modes_of_Introduction, References, Relationships
2019-06-20 CWE Content Team MITRE
updated Related_Attack_Patterns
2020-02-24 CWE Content Team MITRE
updated Applicable_Platforms, Potential_Mitigations, Relationships
2020-06-25 CWE Content Team MITRE
updated Demonstrative_Examples, Potential_Mitigations
2021-07-20 CWE Content Team MITRE
updated Potential_Mitigations
2021-10-28 CWE Content Team MITRE
updated Relationships
2022-10-13 CWE Content Team MITRE
updated Relationships
2023-01-31 CWE Content Team MITRE
updated Description, Related_Attack_Patterns
2023-04-27 CWE Content Team MITRE
updated Relationships
2023-06-29 CWE Content Team MITRE
updated Mapping_Notes, Relationships
2024-11-19
(CWE 4.16, 2024-11-19) 		CWE Content Team MITRE
updated References
Page Last Updated: November 19, 2024
 

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