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

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.

ThreatScore

Threat Mapped score: 0.0

Industry: Finiancial

Threat priority: Unclassified

Observed Examples (CVEs)

CVE: CVE-2000-1218

DNS server can accept DNS updates from hosts that it did not query, leading to cache poisoning
CVE: CVE-2005-0877

DNS server can accept DNS updates from hosts that it did not query, leading to cache poisoning
CVE: CVE-2001-1452

DNS server caches glue records received from non-delegated name servers

Related Attack Patterns (CAPEC)

Attack TTPs

N/A

Modes of Introduction

Phase	Note
Architecture and Design	N/A
Implementation	REALIZATION: This weakness is caused during implementation of an architectural security tactic.

Common Consequences

Impact: Gain Privileges or Assume Identity, Varies by Context — Notes: An attacker can access any functionality that is inadvertently accessible to the source.

Potential Mitigations

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. (N/A)

Applicable Platforms

None (Not Language-Specific, Undetermined)

Demonstrative Examples

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

Body: 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.

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); } }

Intro: 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:

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

// 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; } } }

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.

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