Distributed Component Object Model

T1021.003

Sub-technique of T1021 Remote Services.View on attack.mitre.org

About this technique

Adversaries may use Valid Accounts to interact with remote machines by taking advantage of Distributed Component Object Model (DCOM). The adversary may then perform actions as the logged-on user.

The Windows Component Object Model (COM) is a component of the native Windows application programming interface (API) that enables interaction between software objects, or executable code that implements one or more interfaces. Through COM, a client object can call methods of server objects, which are typically Dynamic Link Libraries (DLL) or executables (EXE). Distributed COM (DCOM) is transparent middleware that extends the functionality of COM beyond a local computer using remote procedure call (RPC) technology.

Permissions to interact with local and remote server COM objects are specified by access control lists (ACL) in the Registry. By default, only Administrators may remotely activate and launch COM objects through DCOM.

Through DCOM, adversaries operating in the context of an appropriately privileged user can remotely obtain arbitrary and even direct shellcode execution through Office applications as well as other Windows objects that contain insecure methods. DCOM can also execute macros in existing documents and may also invoke Dynamic Data Exchange (DDE) execution directly through a COM created instance of a Microsoft Office application, bypassing the need for a malicious document. DCOM can be used as a method of remotely interacting with Windows Management Instrumentation.

Detection rules24

Rules on DetectionCode tagged with T1021.003.

Sigma13

Rule	Level	Log source
Potential DCOM InternetExplorer.Application DLL Hijack	critical	windows / file_event
Potential DCOM InternetExplorer.Application DLL Hijack - Image Load	critical	windows / image_load
BaaUpdate.exe Suspicious DLL Load	high	windows / image_load
DCOM InternetExplorer.Application Iertutil DLL Hijack - Security	high	windows / NULL
HackTool - Potential Impacket Lateral Movement Activity	high	windows / process_creation
MMC Spawning Windows Shell	high	windows / process_creation
MMC20 Lateral Movement	high	windows / process_creation
Potential Excel.EXE DCOM Lateral Movement Via ActivateMicrosoftApp	high	windows / process_creation
Remote DCOM/WMI Lateral Movement	high	rpc_firewall / application
Suspicious BitLocker Access Agent Update Utility Execution	high	windows / process_creation
Suspicious Speech Runtime Binary Child Process	high	windows / process_creation
Suspicious Non PowerShell WSMAN COM Provider	medium	windows / NULL
Suspicious WSMAN Provider Image Loads	medium	windows / image_load

Splunk11

Rule	Type	Risk	Data source
Impacket Lateral Movement Commandline Parameters	TTP	NULL	Sysmon EventID 1, Windows Event Log Security 4688, CrowdStrike ProcessRollup2
Impacket Lateral Movement smbexec CommandLine Parameters	TTP	NULL	Sysmon EventID 1, Windows Event Log Security 4688, CrowdStrike ProcessRollup2
Impacket Lateral Movement WMIExec Commandline Parameters	TTP	NULL	Sysmon EventID 1, Windows Event Log Security 4688, CrowdStrike ProcessRollup2
Mmc LOLBAS Execution Process Spawn	TTP	NULL	Sysmon EventID 1, Windows Event Log Security 4688, CrowdStrike ProcessRollup2
Possible Lateral Movement PowerShell Spawn	Anomaly	NULL	Sysmon EventID 1, CrowdStrike ProcessRollup2
Remote Process Instantiation via DCOM and PowerShell	TTP	NULL	Sysmon EventID 1, Windows Event Log Security 4688, CrowdStrike ProcessRollup2
Remote Process Instantiation via DCOM and PowerShell Script Block	TTP	NULL	Powershell Script Block Logging 4104
Windows Excel ActiveMicrosoftApp Child Process	Anomaly	NULL	Sysmon EventID 1
Windows Excel Spawning Microsoft Project Application	Anomaly	NULL	Sysmon EventID 1, Windows Event Log Security 4688, CrowdStrike ProcessRollup2
Windows SpeechRuntime COM Hijacking DLL Load	TTP	NULL	Sysmon EventID 7
Windows SpeechRuntime Suspicious Child Process	TTP	NULL	Sysmon EventID 1, Windows Event Log Security 4688, CrowdStrike ProcessRollup2

Groups0

None recorded.

Software3

Campaigns0

None recorded.

Procedure examples3

Software3

Used by	Procedure example
MalwareCobalt Strike	Cobalt Strike can deliver Beacon payloads for lateral movement by leveraging remote COM execution. Cobalt Strike DCOM Jan 2017
ToolEmpire	Empire can utilize `Invoke-DCOM` to leverage remote COM execution for lateral movement. Github PowerShell Empire
ToolSILENTTRINITY	SILENTTRINITY can use `System` namespace methods to execute lateral movement using DCOM. GitHub SILENTTRINITY Modules July 2019

References10

Cyberreason DCOM DDE Lateral Movement Nov 2017 Open source
Tsukerman, P. (2017, November 8). Leveraging Excel DDE for lateral movement via DCOM. Retrieved November 21, 2017.
Enigma DCOM Lateral Movement Jan 2017 Open source
Nelson, M. (2017, January 23). Lateral Movement via DCOM: Round 2. Retrieved November 21, 2017.
Enigma Excel DCOM Sept 2017 Open source
Nelson, M. (2017, September 11). Lateral Movement using Excel.Application and DCOM. Retrieved November 21, 2017.
Enigma MMC20 COM Jan 2017 Open source
Nelson, M. (2017, January 5). Lateral Movement using the MMC20 Application COM Object. Retrieved November 21, 2017.
Enigma Outlook DCOM Lateral Movement Nov 2017 Open source
Nelson, M. (2017, November 16). Lateral Movement using Outlook's CreateObject Method and DotNetToJScript. Retrieved November 21, 2017.
Fireeye Hunting COM June 2019 Open source
Hamilton, C. (2019, June 4). Hunting COM Objects. Retrieved June 10, 2019.
MSDN WMI Open source
Microsoft. (n.d.). Windows Management Instrumentation. Retrieved April 27, 2016.
Microsoft COM Open source
Microsoft. (n.d.). Component Object Model (COM). Retrieved November 22, 2017.
Microsoft COM ACL Open source
Microsoft. (n.d.). DCOM Security Enhancements in Windows XP Service Pack 2 and Windows Server 2003 Service Pack 1. Retrieved November 22, 2017.
Microsoft Process Wide Com Keys Open source
Microsoft. (n.d.). Setting Process-Wide Security Through the Registry. Retrieved November 21, 2017.

Data from MITRE ATT&CK® (Enterprise). ATT&CK® is a registered trademark of The MITRE Corporation.