Webpage security

A method to prevent a web browser add-in from adding secondary content to a user interface displaying a webpage through a web browser, the method comprising:

• communicating, over a network, a request for the webpage to a web server, the webpage comprising a plurality of content items;
• receiving, over the network, a browser-executable security script and a list identifying content items within the plurality of content items on the webpage;
• receiving, over the network, the webpage;
• running the browser-executable security script to monitor attempted changes to the webpage;
• outputting the webpage for display;
• detecting, by the browser-executable security script, an attempt to add a content item to the webpage;
• determining that the content item is not included in the list;
• and
• preventing the content item from being displayed through the web browser while the webpage is being displayed by the web browser.

One or more computer storage media having computer-executable instructions embodied thereon that, when executed, configure a computing device to perform a method to prevent a web browser add-in from adding secondary content to a user interface displaying a webpage through a web browser, the method comprising:

• communicating, over a network, a request for the webpage to a web server;
• receiving, over the network, a browser-executable security script and a list identifying content items within a plurality of content items on the webpage;
• receiving, over the network, the webpage;
• outputting the webpage for display, the webpage comprising a document object model;
• running the browser-executable security script to monitor the webpage by adding an observer to a content item;
• detecting, by the observer, a change to the content item;
• determining that the change is not valid because an identification information for a new content item is not on the list;
• and
• removing the change by reverting to an original document object model.

A method to prevent a web browser add-in from adding secondary content to a user interface displaying a webpage through a web browser, the method comprising:

• communicating, over a network, a request for the webpage to a web server;
• receiving, over the network, a browser-executable security script and a list identifying content items within a plurality of content items on the webpage;
• receiving, over the network, the webpage;
• outputting the webpage for display, the webpage comprising a document object model;
• running the browser-executable security script to monitor the webpage by adding an observer to a content item;
• detecting, by the observer, a change to the content item;
• determining that the change is not valid because an identification information for a new content item is not on the list;
• and
• removing the change by reverting to an original document object model.