PipeShell exfiltration over named pipes

Status: experimental
Severity: medium
Time window: 5m
Log source: product windows, category ['ps_module', 'ps_classic_script', 'ps_script']
Author: mdecrevoisier
Source: github.com/mdecrevoisier/SIGMA-detection-rules

Detects scenarios where an attacker establishes "PipeShell" connection(s) between a server and client(s) in order to move laterally or exfiltrate data. The server side will trigger "ServerStream" IOCs meanwhile the client side will trigger "ClientStream" IOCs. The rule works based on this condition, where at least 2 hosts need to trigger one of the condition.

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1059.001` Command and Scripting Interpreter: PowerShell

Event coverage

Provider	Event	Title
PowerShell	Event ID 4103	Payload Context: ContextInfo User Data: UserData.
PowerShell	Event ID 4104	Creating Scriptblock text (MessageNumber of MessageTotal).
PowerShell	Event ID 800	Event ID 800

Rule body yaml

title: PipeShell exfiltration over named pipes
description: Detects scenarios where an attacker establishes "PipeShell" connection(s) between a server and client(s) in order to move laterally or exfiltrate data. The server side will trigger "ServerStream" IOCs meanwhile the client side will trigger "ClientStream" IOCs. The rule works based on this condition, where at least 2 hosts need to trigger one of the condition.
references:
- https://github.com/mdecrevoisier/EVTX-to-MITRE-Attack/tree/master/TA0002-Execution/T1059.001-PowerShell
- https://github.com/threatexpress/invoke-pipeshell
- https://github.com/p3nt4/Invoke-Piper/blob/master/Invoke-Piper.psm1
- https://sudonull.com/post/25207-Using-Pipes-for-Pivoting
- https://codewhitesec.blogspot.com/2020/01/cve-2019-19470-rumble-in-pipe.html
- https://decoder.cloud/2019/03/06/windows-named-pipes-impersonation/
- https://www.powershellgallery.com/packages/PSNamedPipe/1.0.0.19/Content/Public%5CNew-PSNamedPipeServer.ps1
tags:
- attack.execution
- attack.t1059.001
- attack.exfiltration
author: mdecrevoisier
status: experimental
logsource:
  product: windows
  category:
    - ps_module
    - ps_classic_script
    - ps_script
detection:
  SERVER_powershell_native:
    EventID: 800
    EventData|contains: 'System.IO.Pipes.NamedPipeServerStream'
  SERVER_powershell_modern:
    EventID: 4103
    Payload|contains: 'System.IO.Pipes.NamedPipeServerStream'
  SERVER_powershell_block:
    EventID: 4104
    ScriptBlockText|contains: 'System.IO.Pipes.NamedPipeServerStream'

  CLIENT_powershell_native:
    EventID: 800
    EventData|contains: 'System.IO.Pipes.NamedPipeClientStream'
  CLIENT_spowershell_modern:
    EventID: 4103
    Payload|contains: 'System.IO.Pipes.NamedPipeClientStream'
  CLIENT_powershell_block:
    EventID: 4104
    ScriptBlockText|contains: 'System.IO.Pipes.NamedPipeClientStream'

  condition: (1 of SERVER*) AND (1 of CLIENT*) | count(Computer) > 2
  timeframe: 5m
falsepositives:
- packet manager
level: medium

Stages and Predicates

Stage 0: `condition`

(1 of SERVER*) AND (1 of CLIENT*) | count(Computer) > 2

Stage 1: `SERVER_powershell_native`

SERVER_powershell_native:
  EventID: 800
  EventData|contains: 'System.IO.Pipes.NamedPipeServerStream'

Threshold: > 2

Stage 2: `SERVER_powershell_modern`

SERVER_powershell_modern:
  EventID: 4103
  Payload|contains: 'System.IO.Pipes.NamedPipeServerStream'

Stage 3: `SERVER_powershell_block`

SERVER_powershell_block:
  EventID: 4104
  ScriptBlockText|contains: 'System.IO.Pipes.NamedPipeServerStream'

Stage 4: `CLIENT_powershell_native`

CLIENT_powershell_native:
  EventID: 800
  EventData|contains: 'System.IO.Pipes.NamedPipeClientStream'

Stage 5: `CLIENT_spowershell_modern`

CLIENT_spowershell_modern:
  EventID: 4103
  Payload|contains: 'System.IO.Pipes.NamedPipeClientStream'

Stage 6: `CLIENT_powershell_block`

CLIENT_powershell_block:
  EventID: 4104
  ScriptBlockText|contains: 'System.IO.Pipes.NamedPipeClientStream'

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
`EventData`	match	`System.IO.Pipes.NamedPipeClientStream` `System.IO.Pipes.NamedPipeServerStream`
`Payload`	match	`System.IO.Pipes.NamedPipeClientStream` `System.IO.Pipes.NamedPipeServerStream`
`ScriptBlockText`	match	`System.IO.Pipes.NamedPipeClientStream` `System.IO.Pipes.NamedPipeServerStream`

`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)

PipeShell exfiltration over named pipes

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `SERVER_powershell_native`

Stage 2: `SERVER_powershell_modern`

Stage 3: `SERVER_powershell_block`

Stage 4: `CLIENT_powershell_native`

Stage 5: `CLIENT_spowershell_modern`

Stage 6: `CLIENT_powershell_block`

Indicators

Keyboard shortcuts

Search operators

PipeShell exfiltration over named pipes

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: SERVER_powershell_native

Stage 2: SERVER_powershell_modern

Stage 3: SERVER_powershell_block

Stage 4: CLIENT_powershell_native

Stage 5: CLIENT_spowershell_modern

Stage 6: CLIENT_powershell_block

Indicators

Stage 0: `condition`

Stage 1: `SERVER_powershell_native`

Stage 2: `SERVER_powershell_modern`

Stage 3: `SERVER_powershell_block`

Stage 4: `CLIENT_powershell_native`

Stage 5: `CLIENT_spowershell_modern`

Stage 6: `CLIENT_powershell_block`