Cmstp Execution (Sysmon)

Group by: _time, host
Source: github.com/anvilogic-forge/armory

Adversaries may abuse CMSTP to proxy execution of malicious code. The Microsoft Connection Manager Profile Installer (CMSTP.exe) is a command-line program used to install Connection Manager service profiles. CMSTP.exe accepts an installation information file (INF) as a parameter and installs a service profile leveraged for remote access connections

MITRE ATT&CK coverage

Tactic	Techniques
Stealth	`T1218.003` System Binary Proxy Execution: CMSTP

References

https://lolbas-project.github.io/lolbas/Binaries/Cmstp/

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 1: Process creation

Rule body

id: '13810.20276'
title: Cmstp Execution
description: 'Adversaries may abuse CMSTP to proxy execution of malicious code. The
  Microsoft Connection Manager Profile Installer (CMSTP.exe) is a command-line program
  used to install Connection Manager service profiles. CMSTP.exe accepts an installation
  information file (INF) as a parameter and installs a service profile leveraged for
  remote access connections. Living Off the Land Binary and Scripts (LOLBAS) (LOLBIN)
  Atomics T1218.003 Test #1 Atomics T1218.003 Test #2'
logic_format: Splunk
logic: '`get_endpoint_data` `get_endpoint_data_sysmon` (TERM(EventCode=1) OR "<EventID>1<"
  OR Type=Process) ("cmstp.exe") OR ("/s" "/.inf") OR "/ni" OR "/ns" | regex process="(?i)cmstp|\s+\/s\s+.+\.inf|\s+\/ni\s+.{4,}|\s+\/ns\s+.{4,}"
  | table _time, host, user process, process_*, signature_id, parent_* | bin span=1s
  | stats values(*) as * by _time, host '
techniques:
- defense-evasion:system binary proxy execution:cmstp
technique_id:
- T1218.003
data_category:
- Windows Sysmon
references:
- https://lolbas-project.github.io/lolbas/Binaries/Cmstp/

Stages and Predicates

Stage 1: `search`

`get_endpoint_data` `get_endpoint_data_sysmon` (TERM(EventCode=1) OR "<EventID>1<" OR Type=Process) ("cmstp.exe") OR ("/s" "/.inf") OR "/ni" OR "/ns"

Stage 2: `regex`

| regex process="(?i)cmstp|\s+\/s\s+.+\.inf|\s+\/ni\s+.{4,}|\s+\/ns\s+.{4,}"

Stage 3: `table`

| table _time, host, user process, process_*, signature_id, parent_*

Stage 4: `bucket`

| bin span=1s

Stage 5: `stats`

| stats values(*) as * by _time, host

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`EventCode`	eq	`1` corpus 241 (splunk 225, kusto 15, elastic 1)	`field:"EventID" kind:eq value:"1"`
`process`	regex_match	`"(?i)cmstp` `\s+\/s\s+.+.inf` `\s+\/ni\s+.{4,}` `\s+\/ns\s+.{4,}"` corpus 2 (splunk 2)	`field:"CommandLine" kind:regex_match`

Search terms

These SPL tokens match against raw event text.

Stage	Term
1	`"<EventID>1<"`
1	`"cmstp.exe"`
1	`"/s"`
1	`"/.inf"`
1	`"/ni"`
1	`"/ns"`