Potential Remote PowerShell Session Initiated

Status: test
Severity: high
Log source: product windows, category network_connection
Author: Roberto Rodriguez @Cyb3rWard0g
Source: github.com/SigmaHQ/sigma

Detects a process that initiated a network connection over ports 5985 or 5986 from a non-network service account. This could potentially indicates a remote PowerShell connection.

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1059.001` Command and Scripting Interpreter: PowerShell
Lateral Movement	`T1021.006` Remote Services: Windows Remote Management

Event coverage

Provider	Event	Title
Sysmon	Event ID 3	Network connection

Rule body yaml

title: Potential Remote PowerShell Session Initiated
id: c539afac-c12a-46ed-b1bd-5a5567c9f045
status: test
description: |
    Detects a process that initiated a network connection over ports 5985 or 5986 from a non-network service account.
    This could potentially indicates a remote PowerShell connection.
references:
    - https://threathunterplaybook.com/hunts/windows/190511-RemotePwshExecution/notebook.html
author: Roberto Rodriguez @Cyb3rWard0g
date: 2019-09-12
modified: 2024-02-02
tags:
    - attack.execution
    - attack.t1059.001
    - attack.lateral-movement
    - attack.t1021.006
logsource:
    category: network_connection
    product: windows
detection:
    selection:
        DestinationPort:
            - 5985
            - 5986
        Initiated: 'true' # only matches of the initiating system can be evaluated
        SourceIsIpv6: 'false'
    filter_main_service_users:
        - User|contains: # covers many language settings for Network Service. Please expand
              - 'NETWORK SERVICE'
              - 'NETZWERKDIENST'
              - 'SERVICIO DE RED'
              - 'SERVIZIO DI RETE'
        - User|contains|all:
              - 'SERVICE R'
              - 'SEAU'
    filter_main_localhost:
        SourceIp:
            - '::1'
            - '127.0.0.1'
        DestinationIp:
            - '::1'
            - '127.0.0.1'
    filter_optional_avast:
        Image:
            - 'C:\Program Files\Avast Software\Avast\AvastSvc.exe'
            - 'C:\Program Files (x86)\Avast Software\Avast\AvastSvc.exe'
    condition: selection and not 1 of filter_main_* and not 1 of filter_optional_*
falsepositives:
    - Legitimate usage of remote PowerShell, e.g. remote administration and monitoring.
    - Network Service user name of a not-covered localization
level: high

Stages and Predicates

Stage 0: `condition`

selection and not 1 of filter_main_* and not 1 of filter_optional_*

Stage 1: `selection`

selection:
    DestinationPort:
        - 5985
        - 5986
    Initiated: 'true'
    SourceIsIpv6: 'false'

Stage 2: `not filter_main_*`

filter_main_service_users:
    - User|contains:
          - 'NETWORK SERVICE'
          - 'NETZWERKDIENST'
          - 'SERVICIO DE RED'
          - 'SERVIZIO DI RETE'
    - User|contains|all:
          - 'SERVICE R'
          - 'SEAU'
filter_main_localhost:
    SourceIp:
        - '::1'
        - '127.0.0.1'
    DestinationIp:
        - '::1'
        - '127.0.0.1'

Stage 3: `not filter_optional_avast`

filter_optional_avast:
    Image:
        - 'C:\Program Files\Avast Software\Avast\AvastSvc.exe'
        - 'C:\Program Files (x86)\Avast Software\Avast\AvastSvc.exe'

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

Field	Kind	Excluded values
`DestinationIp`	eq	`127.0.0.1`
`DestinationIp`	eq	`::1`
`SourceIp`	eq	`127.0.0.1`
`SourceIp`	eq	`::1`
`User`	match	`SEAU`
`User`	match	`SERVICE R`
`User`	match	`NETWORK SERVICE`
`User`	match	`NETZWERKDIENST`
`User`	match	`SERVICIO DE RED`
`User`	match	`SERVIZIO DI RETE`
`Image`	eq	`C:\Program Files (x86)\Avast Software\Avast\AvastSvc.exe`
`Image`	eq	`C:\Program Files\Avast Software\Avast\AvastSvc.exe`

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
`DestinationPort`	eq	`5985` corpus 3 (sigma 2, chronicle 1) `5986` corpus 3 (sigma 2, chronicle 1)
`Initiated`	eq	`true` corpus 50 (sigma 50)
`SourceIsIpv6`	eq	`false`

`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)

Potential Remote PowerShell Session Initiated

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection`

Stage 2: `not filter_main_*`

Stage 3: `not filter_optional_avast`

Exclusions

Indicators

Keyboard shortcuts

Search operators

Potential Remote PowerShell Session Initiated

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection

Stage 2: not filter_main_*

Stage 3: not filter_optional_avast

Exclusions

Indicators

Stage 0: `condition`

Stage 1: `selection`

Stage 2: `not filter_main_*`

Stage 3: `not filter_optional_avast`