Detect Distributed Component Object Model in Elastic Security
Adversaries may use Valid Accounts to interact with remote machines by taking advantage of Distributed Component Object Model (DCOM). DCOM extends Windows COM (Component Object Model) beyond local machines using RPC, allowing remote method calls on COM objects. Adversaries with Administrator privileges can remotely obtain code execution through Office applications (Excel, Outlook), MMC20.Application, ShellWindows, and other insecure COM objects. Tools like Empire's Invoke-DCOM, Cobalt Strike, and SILENTTRINITY have built-in DCOM lateral movement capabilities. DCOM communicates over TCP port 135 (RPC endpoint mapper) and dynamically assigned high ports.
MITRE ATT&CK
- Tactic
- Lateral Movement
- Technique
- T1021 Remote Services
- Sub-technique
- T1021.003 Distributed Component Object Model
- Canonical reference
- https://attack.mitre.org/techniques/T1021/003/
Elastic Detection Query
process where event.type == "start" and
(
(
process.parent.name in~ ("mmc.exe", "excel.exe", "winword.exe", "outlook.exe", "powerpnt.exe", "visio.exe") and
process.name in~ ("cmd.exe", "powershell.exe", "wscript.exe", "cscript.exe", "mshta.exe", "rundll32.exe", "regsvr32.exe", "certutil.exe")
) or
process.name == "dcomcnfg.exe" or
(
process.command_line : "*DCOM*" and process.command_line : "*-Exec*"
)
)Detects DCOM lateral movement by identifying suspicious child processes spawned from COM host applications (mmc.exe, Office apps), direct execution of the DCOM configuration tool, and command-line references to DCOM execution. Uses Elastic Common Schema (ECS) process fields against Winlogbeat or Elastic Agent Sysmon data.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate IT administrators using mmc.exe to spawn PowerShell for authorized remote management tasks on managed endpoints
- Security tools or EDR agents that use COM automation to invoke cmd.exe or PowerShell as part of scheduled scans or remediation workflows
- Software deployment platforms (SCCM, Intune) that legitimately leverage Office application COM interfaces to run scripts during patch cycles
- Excel macro-based automation in finance or operations environments where Excel spawns wscript.exe or cmd.exe for approved business logic
Other platforms for T1021.003
Testing Methodology
Validate this detection against 3 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 1DCOM Lateral Movement via MMC20.Application
Expected signal: Sysmon Event ID 1: powershell.exe process with MMC20.Application in command line. Sysmon Event ID 3: outbound connection to 127.0.0.1 on port 135 and dynamic RPC port. Sysmon Event ID 1 on target: mmc.exe spawning cmd.exe. Sysmon Event ID 11: dcom_test.txt file created in C:\Windows\Temp.
- Test 2DCOM Lateral Movement via ShellWindows
Expected signal: Sysmon Event ID 1: powershell.exe with CLSID 9BA05972 in command line. Sysmon Event ID 3: connection to 127.0.0.1:135. Sysmon Event ID 1: explorer.exe or svchost spawning cmd.exe on the target.
- Test 3Query DCOM Configuration via dcomcnfg
Expected signal: Sysmon Event ID 1: Process Create for dcomcnfg.exe. Security Event ID 4688 (if command-line auditing enabled). The process tree will show dcomcnfg.exe spawning mmc.exe as a child.
References (7)
- https://attack.mitre.org/techniques/T1021/003/
- https://enigma0x3.net/2017/01/05/lateral-movement-using-the-mmc20-application-com-object/
- https://enigma0x3.net/2017/01/23/lateral-movement-via-dcom-round-2/
- https://www.fireeye.com/blog/threat-research/2019/06/hunting-com-objects.html
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1021.003/T1021.003.md
- https://github.com/EmpireProject/Empire/blob/master/data/module_source/lateral_movement/Invoke-DCOM.ps1
- https://learn.microsoft.com/en-us/windows/win32/com/the-component-object-model
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