Detect Dynamic Data Exchange in Google Chronicle
Adversaries may use Windows Dynamic Data Exchange (DDE) to execute arbitrary commands without relying on VBA macros. DDE is a legacy client-server IPC protocol supported in Microsoft Office applications that allows documents to request command execution from a server process. Attackers poison Word documents, Excel spreadsheets, Outlook emails, and CSV files with DDE fields (e.g., DDEAUTO cmd) that execute shell commands when the document is opened and field updates are accepted. DDE is also delivered via OLE-embedded Equation Editor objects (EQNEDT32.EXE) exploiting CVE-2017-11882. Threat actors including APT28, FIN7, MuddyWater, Cobalt Group, Gallmaker, APT37, Leviathan, and BITTER have leveraged DDE in targeted spearphishing campaigns to achieve initial code execution.
MITRE ATT&CK
- Tactic
- Execution
- Technique
- T1559 Inter-Process Communication
- Sub-technique
- T1559.002 Dynamic Data Exchange
- Canonical reference
- https://attack.mitre.org/techniques/T1559/002/
YARA-L Detection Query
rule dde_office_suspicious_child_spawn {
meta:
author = "Detection Engineering"
description = "Detects DDE abuse via suspicious child process spawning from Microsoft Office applications or EQNEDT32.EXE (CVE-2017-11882)"
severity = "HIGH"
priority = "HIGH"
mitre_attack_tactic = "Execution"
mitre_attack_technique = "T1559.002"
reference = "https://attack.mitre.org/techniques/T1559/002/"
created = "2024-01-01"
events:
$e.metadata.event_type = "PROCESS_LAUNCH"
$e.principal.process.file.full_path != ""
// Office parent or Equation Editor
(
re.regex($e.principal.process.file.full_path, `(?i)(winword\.exe|excel\.exe|outlook\.exe|onenote\.exe|powerpnt\.exe|msaccess\.exe|mspub\.exe|EQNEDT32\.EXE)$`)
)
// Suspicious child process
re.regex($e.target.process.file.full_path, `(?i)(\\cmd\.exe|\\powershell\.exe|\\pwsh\.exe|\\wscript\.exe|\\cscript\.exe|\\mshta\.exe|\\rundll32\.exe|\\regsvr32\.exe|\\certutil\.exe|\\bitsadmin\.exe|\\msiexec\.exe|\\wmic\.exe|\\schtasks\.exe|\\net\.exe|\\net1\.exe|\\curl\.exe|\\wget\.exe|\\forfiles\.exe|\\pcalua\.exe)$`)
condition:
$e
}Chronicle YARA-L 2.0 rule detecting DDE-based execution (T1559.002) by matching PROCESS_LAUNCH events where Microsoft Office applications or EQNEDT32.EXE are the initiating process and known LOLBin/interpreter processes are spawned as children. Covers both DDEAUTO field abuse and Equation Editor CVE-2017-11882 exploitation.
Data Sources
Required Tables
False Positives & Tuning
- Enterprise RPA (Robotic Process Automation) solutions like UiPath or Blue Prism that drive Office applications and spawn child processes as part of attended/unattended automation flows
- Legitimate Office COM automation from server-side document conversion services (e.g., LibreOffice wrappers, Word to PDF pipelines) that inherit Office process parentage
- Security testing or red team exercises against endpoints where EQNEDT32.EXE is intentionally invoked to validate EDR detection coverage
Other platforms for T1559.002
Testing Methodology
Validate this detection against 4 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1CSV DDE Injection via Excel
Expected signal: Sysmon Event ID 1: Process Create for excel.exe with the CSV path as argument. If the DDE prompt is accepted: Sysmon Event ID 1 for cmd.exe with ParentImage=excel.exe and CommandLine='/c whoami > %TEMP%\dde_csv_out.txt'. Sysmon Event ID 11: File Create for dde_csv_out.txt in %TEMP%. Security Event ID 4688 (if command line auditing enabled) for the cmd.exe spawn.
- Test 2Word DDEAUTO Field Execution via RTF
Expected signal: Sysmon Event ID 1: Process Create for winword.exe with the RTF file as argument. If DDE executes: Sysmon Event ID 1 for cmd.exe with ParentImage=winword.exe, CommandLine='/c whoami > %TEMP%\dde_word_out.txt'. Sysmon Event ID 11: File Create for dde_word_out.txt. Office telemetry logs the DDEAUTO field activation attempt. Security Event ID 4688 for the spawned cmd.exe.
- Test 3DDE via Outlook Email with Embedded OLE Object
Expected signal: Sysmon Event ID 1: Process Create for outlook.exe with the .msg file path as argument. Outlook COM instantiation visible in Sysmon Event ID 1 for the PowerShell parent spawning outlook.exe. If OLE DDE executes: Sysmon Event ID 1 for cmd.exe with ParentImage=outlook.exe. Security Event ID 4688 for the spawned process.
- Test 4Equation Editor (EQNEDT32.EXE) Presence and Execution Check
Expected signal: If EQNEDT32.EXE is found and executed: Sysmon Event ID 1 for EQNEDT32.EXE with Image=<office_path>\EQNEDT32.EXE. Prefetch file created at C:\Windows\Prefetch\EQNEDT32.EXE-*.pf. Security Event ID 4688 for EQNEDT32.EXE execution. In a real exploitation scenario: Sysmon Event ID 1 for a child process (cmd.exe, powershell.exe) with ParentImage=EQNEDT32.EXE would additionally fire.
References (12)
- https://attack.mitre.org/techniques/T1559/002/
- https://www.bleepingcomputer.com/news/microsoft/microsoft-disables-dde-feature-in-word-to-prevent-further-malware-attacks/
- https://sensepost.com/blog/2016/powershell-c-sharp-and-dde-the-power-within/
- https://sensepost.com/blog/2017/macro-less-code-exec-in-msword/
- https://posts.specterops.io/reviving-dde-using-onenote-and-excel-for-code-execution-d7226864caee
- https://portal.msrc.microsoft.com/security-guidance/advisory/ADV170021
- https://technet.microsoft.com/library/security/4053440
- https://owasp.org/www-community/attacks/CSV_Injection
- https://blog.securelayer7.net/how-to-perform-csv-excel-macro-injection/
- https://www.fireeye.com/blog/threat-research/2019/06/hunting-com-objects.html
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1559.002/T1559.002.md
- https://learn.microsoft.com/en-us/defender-endpoint/advanced-hunting-deviceprocessevents-table
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