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.
This weakness can lead to a wide variety of resultant weaknesses, depending on the behavior of the exposed method. It can apply to any number of technologies and approaches, such as ActiveX controls, Java functions, IOCTLs, and so on. The exposure can occur in a few different ways: The function/method was never intended to be exposed to outside actors. The function/method was only intended to be accessible to a limited set of actors, such as Internet-based access from a single web site.
Threat Mapped score: 0.0
Industry: Finiancial
Threat priority: Unclassified
CVE: CVE-2007-6382
arbitrary Java code execution via exposed method
CVE: CVE-2007-1112
security tool ActiveX control allows download or upload of files
N/A
| Phase | Note |
|---|---|
| Architecture and Design | N/A |
| Implementation | N/A |
Intro: In the following Java example the method removeDatabase will delete the database with the name specified in the input parameter.
Body: 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.
public void removeDatabase(String databaseName) { try { Statement stmt = conn.createStatement(); stmt.execute("DROP DATABASE " + databaseName); } catch (SQLException ex) {...} }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; } } }Intro: 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:
Body: 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.
public class WebViewGUI extends Activity { WebView mainWebView; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); mainWebView = new WebView(this); mainWebView.getSettings().setJavaScriptEnabled(true); mainWebView.addJavascriptInterface(new JavaScriptInterface(), "userInfoObject"); mainWebView.loadUrl("file:///android_asset/www/index.html"); setContentView(mainWebView); } final class JavaScriptInterface { JavaScriptInterface () {} public String getUserInfo() { return currentUser.Info(); } } }Intro: After Android 4.2, only methods annotated with @JavascriptInterface are available in JavaScript, protecting usage of getClass() by default, as in this example:
Body: 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:
final class JavaScriptInterface { JavaScriptInterface () { } @JavascriptInterface public String getUserInfo() { return currentUser.Info(); } }