Inter-Process Communication: Dynamic Data Exchange
Adversaries may use Windows Dynamic Data Exchange (DDE) to execute arbitrary commands. DDE is a client-server protocol for one-time and/or continuous inter-process communication (IPC) between applications. Once a link is established, applications can autonomously exchange transactions consisting of strings, warm data links (notifications when a data item changes), hot data links (duplications of changes to a data item), and requests for command execution.
Object Linking and Embedding (OLE), or the ability to link data between documents, was originally implemented through DDE. Despite being superseded by Component Object Model, DDE may be enabled in Windows 10 and most of Microsoft Office 2016 via Registry keys.   
Microsoft Office documents can be poisoned with DDE commands  , directly or through embedded files , and used to deliver execution via Phishing campaigns or hosted Web content, avoiding the use of Visual Basic for Applications (VBA) macros.  DDE could also be leveraged by an adversary operating on a compromised machine who does not have direct access to a Command and Scripting Interpreter.
|Application Isolation and Sandboxing||
Ensure Protected View is enabled.
|Behavior Prevention on Endpoint|
|Disable or Remove Feature or Program||
Registry keys specific to Microsoft Office feature control security can be set to disable automatic DDE/OLE execution.  Microsoft also created, and enabled by default, Registry keys to completely disable DDE execution in Word and Excel.
Monitor processes for abnormal behavior indicative of DDE abuse, such as Microsoft Office applications loading DLLs and other modules not typically associated with the application or these applications spawning unusual processes (such as cmd.exe).
OLE and Office Open XML files can be scanned for ‘DDEAUTO', ‘DDE’, and other strings indicative of DDE execution.
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