Cross domain access to object constructors can be used to facilitate cross-site scripting

2012-11-02T00:00:00
ID OPERA:1032
Type opera
Reporter Opera
Modified 2012-11-02T00:00:00

Description

JavaScripts are able to redefine and override the methods of native objects. They may also do this with the native objects of any document that shares the same origin. By redefining the methods of another document through the constructor property of the document's host objects, a malicious script can cause Opera to override methods of native objects in documents from different origins. When scripts in those target documents then access those methods, they run the scripts defined by the malicious document, in the context of the target site. This allows cross-site scripting (XSS) attacks.