ActiveX

ActiveX is a deprecated software framework created by Microsoft (1996) that adapts Component Object Model (COM) and Object Linking and Embedding (OLE) technologies for content upload/downloaded from a network, particularly the Internet.
https://en.wikipedia.org/wiki/ActiveX#:~:text=Microsoft%20introduced%20ActiveX%20in%201996,ActiveX%20controls%20contain%20compiled%20code.

Many organisations are dependent on legacy ActiveX-based web applications for example to track product inventory and generate reports, which has resulted in extentions for modern browsers being released such as "IE Tab".
https://chrome.google.com/webstore/detail/ie-tab/hehijbfgiekmjfkfjpbkbammjbdenadd

Using Cybersecurity controls to block access to online resources based upon Categorisation, Deny Lists, Firewall rules etc is not effective as Data Loss Prevention technologies.
For users who have the capability to use ActiveX technology, the use of this upload method demonstrates they can easily move sensitive/confidential data outside of organisations.

Supporting legacy technologies increases the scope by which data can be transferred out of organisations, and the associated likelihood of a Data Loss risk event occurring must be considered.
The impact of a Data Loss risk event will depend on the content and amount of information that has been uploaded via the ActiveX upload method.

Use DLP-TEST to assess: - 

- Coverage of DLP Technologies to detect data being uploaded via the ActiveX method.
- Capability of DLP Technologies to accurately detect sensitive/confidential data being uploaded via the ActiveX method.
- Ability of DLP technologies to ignore data being uploaded that is NOT sensitive or confidential.