Dynamic Data Exchange

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Dynamic Data Exchange
Technique
ID T1173
Tactic Execution
Platform Windows
Permissions Required User
Data Sources API monitoring, DLL monitoring, Process Monitoring, Windows Registry, Windows event logs
Supports Remote No

Windows Dynamic Data Exchange (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 Despite being superseded by COM, DDE is still enabled in Windows 10 and most of Microsoft Office 2016 (a December 2017 patch created a Registry key that disables DDE in Word by default).1

Adversaries may use DDE to execute arbitrary commands. Microsoft Office documents can be poisoned with DDE commands23 and used to deliver execution via spear phishing campaigns or hosted Web content, avoiding the use of Visual Basic for Applications (VBA) macros.4 DDE could also be leveraged by an adversary operating on a compromised machine who does not have direct access to command line execution.

Examples

  • APT28 has delivered JHUHUGIT by executing PowerShell commands through DDE in Word documents. 56
  • FIN7 spear phishing campaigns have included malicious Word documents with DDE execution.7

Mitigation

Ensure Protected View is enabled.8

Registry keys specific to Microsoft Office feature control security can be set to disable automatic DDE/OLE execution.91

Detection

OLE and Office Open XML files can be scanned for ‘DDEAUTO', ‘DDE’, and other strings indicative of DDE execution.10

Monitor for Microsoft Office applications loading DLLs and other modules not typically associated with the application.

Monitor for spawning of unusual processes (such as cmd.exe) from Microsoft Office applications.