CWE-749: Exposed Dangerous Method or Function | Glexia
CWE-749 (Exposed Dangerous Method or Function) weakness overview with consequences, detection methods, mitigations, related CVEs and MITRE ATT&CK context.
Glexia's Take · Automated analysis
CWE-749: Exposed Dangerous Method or Function
Exposed Dangerous Method or Function represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Executive Impact
- Integrity,Confidentiality,Availability,Access Control,Other: Gain Privileges or Assume Identity,Read Application Data,Modify Application Data,Execute Unauthorized Code or Commands,Other: Exposing critical functionality essentially provides an attacker with the privilege level of the exposed functionality. This could result in the modification or exposure of sensitive data or possibly even execution of arbitrary code.
Developer Pattern
CWE-749 is the kind of defect developers can usually prevent with explicit validation, safer framework defaults, and tests that exercise hostile input or unsafe state transitions.
Automation confidence
high confidence from CWE-749, 4.20.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Official CWE Definition
CWE-749: Exposed Dangerous Method or Function
The product provides an Applications Programming Interface (API) or similar interface for interaction with external actors, but the interface includes a dangerous method or function that is not properly restricted.
Developer And Remediation Guidance
How teams prevent and detect this weakness
Causes
- In the following Java example the method removeDatabase will delete the database with the name specified in the input parameter. The method in this example is declared public and therefore is exposed to any class in the application. Deleting a database should be considered a critical operation within an application and access to this potentially dangerous method should be restricted. Within Java this can be accomplished simply by declaring the method private thereby exposing it only to the enclosing class as in the following example.
- 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: A call into native code can then be initiated by passing parameters within the URL:,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.
- This application uses a WebView to display websites, and creates a Javascript interface to a Java object to allow enhanced functionality on a trusted website: Before Android 4.2 all methods, including inherited ones, are exposed to Javascript when using addJavascriptInterface(). This means that a malicious website loaded within this WebView can use reflection to acquire a reference to arbitrary Java objects. This will allow the website code to perform any action the parent application is authorized to.,For example, if the application has permission to send text messages:,This malicious script can use the userInfoObject object to load the SmsManager object and send arbitrary text messages to any recipient.
- After Android 4.2, only methods annotated with @JavascriptInterface are available in JavaScript, protecting usage of getClass() by default, as in this example: This code is not vulnerable to the above attack, but still may expose user info to malicious pages loaded in the WebView. Even malicious iframes loaded within a trusted page may access the exposed interface:,This malicious code within an iframe is able to access the interface object and steal the user's data.
Remediation
- Architecture and Design: If you must expose a method, make sure to perform input validation on all arguments, limit access to authorized parties, and protect against all possible vulnerabilities.
- Architecture and Design,Implementation:
Detection
- 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.)
Mappings
Related CVEs, CWEs, and ATT&CK context
Related CWEs
ATT&CK Relevance
ATT&CK relevance is shown only when reviewed or responsibly inferred.