Visual Studio Code Tunnel Execution (Windows Event Log)

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

Adversaries may communicate using application layer protocols associated with web traffic to avoid detection/network filtering by blending in with existing traffic. Commands to the remote system, and often the results of those commands, will be embedded within the protocol traffic between the client and server. This use case detects the execution of Visual Studio Code tunnel in attempt to establish a C2 channel, accounting for instances where the binary has been renamed.

MITRE ATT&CK coverage

Tactic	Techniques
Command & Control	`T1071.001` Application Layer Protocol: Web Protocols

References

Event coverage

Provider	Event	Title
Security-Auditing	Event ID 4688	A new process has been created.

Rule body yaml

id: '40420.73843'
title: Visual Studio Code Tunnel Execution
description: Adversaries may communicate using application layer protocols associated
  with web traffic to avoid detection/network filtering by blending in with existing
  traffic. Commands to the remote system, and often the results of those commands,
  will be embedded within the protocol traffic between the client and server. This
  use case detects the execution of Visual Studio Code tunnel in attempt to establish
  a C2 channel, accounting for instances where the binary has been renamed.
logic_format: Splunk
logic: '`get_endpoint_data` `get_endpoint_data_winevent` (TERM(EventCode=4688) OR
  "<EventID>4688<" OR Type=Process) "tunnel" OR ("tunnel" ("--name " "--accept-server-license-terms")
  OR "--cli-data-dir") OR ("cmd.exe" " /d " " /c " "\\servers\\Stable-" "code-server.cmd")
  | where match(process, "(?i)\.exe(\x22)?\s+tunnel\s?") or ((match(process, "\.exe(\x22)?\s+tunnel\s?$")
  and like(process, "%--name %") and like(process, "%--accept-server-license-terms%"))
  or like(process, "%--cli-data-dir%") or (like(process_path, "%cmd.exe") and like(process,
  "% /d %") and like(process, "% /c %") and like(process, "%\\servers\\Stable-%")
  and like(process, "%code-server.cmd%"))) | table _time, host, user, process, process_*,
  parent_* | bin span=1s | stats values(*) as * by _time, host '
techniques:
- command-and-control:application layer protocol:web protocols
technique_id:
- T1071.001
data_category:
- Process command-line parameters
- Windows event logs
references:
- https://detection.fyi/sigmahq/sigma/windows/process_creation/proc_creation_win_vscode_tunnel_execution/
- https://attack.mitre.org/techniques/T1071/001/
- https://www.sentinelone.com/labs/operation-digital-eye-chinese-apt-compromises-critical-digital-infrastructure-via-visual-studio-code-tunnels/

Stages and Predicates

Stage 1: `search`

`get_endpoint_data` `get_endpoint_data_winevent` (TERM(EventCode=4688) OR "<EventID>4688<" OR Type=Process) "tunnel" OR ("tunnel" ("--name " "--accept-server-license-terms") OR "--cli-data-dir") OR ("cmd.exe" " /d " " /c " "\\servers\\Stable-" "code-server.cmd")

Stage 2: `where`

| where match(process, "(?i)\.exe(\x22)?\s+tunnel\s?") or ((match(process, "\.exe(\x22)?\s+tunnel\s?$") and like(process, "%--name %") and like(process, "%--accept-server-license-terms%")) or like(process, "%--cli-data-dir%") or (like(process_path, "%cmd.exe") and like(process, "% /d %") and like(process, "% /c %") and like(process, "%\\servers\\Stable-%") and like(process, "%code-server.cmd%")))

Stage 3: `table`

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

Stage 4: `bucket`

| bin span=1s

Stage 5: `stats`

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

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

Field	Kind	Values
`EventCode`	eq	`4688` corpus 313 (splunk 283, kusto 30)
`process`	like	`"% /c %"` corpus 6 (sigma 4, splunk 2) `"% /d %"` corpus 3 (sigma 2, splunk 1) `"%--accept-server-license-terms%"` corpus 4 (sigma 3, splunk 1) `"%--cli-data-dir%"` `"%--name %"` `"%\\servers\\Stable-%"` `"%code-server.cmd%"` corpus 3 (sigma 2, splunk 1)
`process`	match	`"(?i)\.exe(\x22)?\s+tunnel\s?"` `"\.exe(\x22)?\s+tunnel\s?$"`
`process_path`	like	`"%cmd.exe"` corpus 2 (sigma 1, splunk 1)

Search terms

Bare-string tokens in the SPL search body. Splunk matches each token against _raw (the untyped raw event text) anywhere it appears, not against a specific field. These don't surface in the Indicators table because they aren't predicates on a known field.

Stage	Term
1	`TERM`
1	`"<EventID>4688<"`
1	`"tunnel"`
1	`"tunnel"`
1	`"--name "`
1	`"--accept-server-license-terms"`
1	`"--cli-data-dir"`
1	`"cmd.exe"`
1	`" /d "`
1	`" /c "`
1	`"\\servers\\Stable-"`
1	`"code-server.cmd"`

`j` / `k`	Scroll down / up
`d` / `u`	Half-page down / up
`gg` / `G`	Top / bottom
`h` / `l`	History back / forward
`f`	Follow link (`Shift` = new tab)
`/`	Focus search
`?`	Toggle this help
`↑` / `↓`	Navigate search results
`Enter`	Open highlighted result
`Esc`	Close results / dialog

`type:`	`events` / `rules` / `providers`
`vendor:`	`sigma` / `elastic` / `splunk` / `kusto` / `chronicle` (vendor name alone also works: `sigma:`, `kql:`, `secops:`…)
`tactic:`	TA-id, slug, or name: `credential_access`, `TA0006`
`technique:`	technique or sub-technique ID: `T1003`, `T1003.001` (alias `tech:`)
`severity:`	`critical` / `high` / `medium` / `low` / `informational` (alias `sev:`)
`risk_score`	Numeric comparison on the Elastic risk score (0 to 100): `risk_score>50`, `risk_score<=20`, `risk_score=99` (alias `risk`; Elastic rules only)
`stages:`	Rules with exactly N pipeline stages
`correlation:`	`single_event` / `sequence` / `alternatives` / `alternatives_cross_log` / `all_required` / `correlated`
`with:`	Co-occurrence event-id; stacks (`with:4624 with:4769`) to require all, while a comma list in one occurrence (`with:4624,4769`) is an either-or group. Implies multi-event
`like:`	Structural neighbors of a rule slug (equivalents + subsumption stricter / broader): `like:comsvcs_lsass_memory_dump-splunk-sysmon`
`groupby:`	Entity-grouping substring match against `group_by_keys`: `groupby:user`, `groupby:host`
`uses:`	Rules whose predicate tree touches the field (any kind, any value): `uses:CommandLine`
`excludes:`	Rules with top-level `not()` clauses on the field (FP whitelists): `excludes:ParentImage`
`field:` / `value:`	Predicate search; narrows rule cards to those with a matching leaf and drives the indicator tier. Unquoted = substring, wildcards allowed (`value:mimikatz`)
`indicator:`	Shorthand for `field:F value:V`: `indicator:Image=*\powershell.exe`
`kind:`	Filter by predicate kind. Narrows rule cards to those carrying a matching predicate leaf (`vendor:elastic kind:cidr_match`) and drives the indicator tier: `contains` / `starts_with` / `ends_with` / `regex` / `cidr` / `eq` / `in` … (operator aliases `op:`/`match:`)
`has:` / `no:`	`sample`, `field`, `notes`, `refs`, `trace`, `thirdparty`, `rule`, `pattern`, `timewindow`, `threshold`, `newterms`, `sigma`/`elastic`/`splunk`/`kusto`/`chronicle`
`-op:val`	Exclude matches; works on most operators but not `type:`/`like:`/`has:`/`no:` (use `no:<flag>` to exclude a rule flag): `tactic:execution -vendor:splunk`. Standalone `-kind:`/`-field:`/`-value:` drop every rule carrying a matching predicate leaf (`type:rules -kind:is_null`)
`field:"…"` / `value:"…"`	Quoted value = anchored exact match (also allows spaces): `value:"net user"`
`a,b`	Comma = OR inside one operator (`vendor:sigma,elastic`, `severity:high,critical`); repeating a facet merges the same way. `field:`/`value:` never split (literal commas)
`vendors:` / `stage:`	Singular and plural spellings fold to the canonical operator and value: `tactics:` = `tactic:`, `type:event` = `type:events`, `correlation:sequences` = `correlation:sequence`, `has:thresholds` = `has:threshold`
`"quoted phrase"`	Exact-match a multi-word phrase (free text)

Visual Studio Code Tunnel Execution (Windows Event Log)

MITRE ATT&CK coverage

References

Event coverage

Rule body yaml

Stages and Predicates

Stage 1: `search`

Stage 2: `where`

Stage 3: `table`

Stage 4: `bucket`

Stage 5: `stats`

Indicators

Search terms

Keyboard shortcuts

Search operators

Visual Studio Code Tunnel Execution (Windows Event Log)

MITRE ATT&CK coverage

References

Event coverage

Rule body yaml

Stages and Predicates

Stage 1: search

Stage 2: where

Stage 3: table

Stage 4: bucket

Stage 5: stats

Indicators

Search terms

Stage 1: `search`

Stage 2: `where`

Stage 3: `table`

Stage 4: `bucket`

Stage 5: `stats`