The software 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: 1) The function/method was never intended to be exposed to outside actors. 2) 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. 800 Category ChildOf 808 1000 699 Weakness ChildOf 485 1000 Weakness ChildOf 691 888 Category ChildOf 907 Primary Architecture and Design Implementation Low to Medium Integrity Confidentiality Availability Access_Control Other Gain privileges / 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. 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 Identify and Reduce Attack Surface Identify all exposed functionality. Explicitly list all functionality that must be exposed to some user or set of users. Identify which functionality may be: accessible to all users restricted to a small set of privileged users prevented from being directly accessible at all Ensure that the implemented code follows these expectations. This includes setting the appropriate access modifiers where applicable (public, private, protected, etc.) or not marking ActiveX controls safe-for-scripting. In the following Java example the method removeDatabase will delete the database with the name specified in the input parameter. Java public void removeDatabase(String databaseName) { try { Statement stmt = conn.createStatement(); stmt.execute("DROP DATABASE " + databaseName); } catch (SQLException ex) {...} } 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. Java private void removeDatabase(String databaseName) { try { Statement stmt = conn.createStatement(); stmt.execute("DROP DATABASE " + databaseName); } catch (SQLException ex) {...} } CVE-2007-6382 arbitrary Java code execution via exposed method CVE-2007-1112 security tool ActiveX control allows download or upload of files Under-reported and under-studied. This weakness could appear in any technology, language, or framework that allows the programmer to provide a functional interface to external parties, but it is not heavily reported. In 2007, CVE began showing a notable increase in reports of exposed method vulnerabilities in ActiveX applications, as well as IOCTL access to OS-level resources. These weaknesses have been documented for Java applications in various secure programming sources, but there are few reports in CVE, which suggests limited awareness in most parts of the vulnerability research community. http://msdn.microsoft.com/workshop/components/activex/safety.asp http://msdn.microsoft.com/workshop/components/activex/security.asp 2008-11-24 CWE Content Team MITRE 2009-01-12 updated Name CWE Content Team MITRE 2009-07-27 updated Relationships CWE Content Team MITRE 2009-12-28 updated Applicable_Platforms, Likelihood_of_Exploit CWE Content Team MITRE 2010-02-16 updated Common_Consequences, Demonstrative_Examples, Potential_Mitigations, References, Related_Attack_Patterns, Relationships CWE Content Team MITRE 2010-04-05 updated Demonstrative_Examples, Related_Attack_Patterns CWE Content Team MITRE 2010-06-21 updated Common_Consequences CWE Content Team MITRE 2011-06-01 updated Common_Consequences CWE Content Team MITRE 2012-05-11 updated Relationships Exposed Insecure Method or Function