Change PowerShell Policies to an Insecure Level

Status: test
Severity: medium
Log source: product windows, category process_creation
Author: frack113
Source: github.com/SigmaHQ/sigma

Detects changing the PowerShell script execution policy to a potentially insecure level using the "-ExecutionPolicy" flag.

MITRE ATT&CK coverage

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

Event coverage

Provider	Event	Title
Sysmon	Event ID 1	Process creation

Rule body yaml

title: Change PowerShell Policies to an Insecure Level
id: 87e3c4e8-a6a8-4ad9-bb4f-46e7ff99a180
related:
    - id: cf2e938e-9a3e-4fe8-a347-411642b28a9f # ProcCreation Registry
      type: similar
    - id: 61d0475c-173f-4844-86f7-f3eebae1c66b # ScriptBlock
      type: similar
    - id: fad91067-08c5-4d1a-8d8c-d96a21b37814 # Registry
      type: similar
status: test
description: Detects changing the PowerShell script execution policy to a potentially insecure level using the "-ExecutionPolicy" flag.
references:
    - https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.security/set-executionpolicy?view=powershell-7.4
    - https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_execution_policies?view=powershell-7.4
    - https://adsecurity.org/?p=2604
    - https://thedfirreport.com/2021/11/01/from-zero-to-domain-admin/
author: frack113
date: 2021-11-01
modified: 2025-10-07
tags:
    - attack.execution
    - attack.t1059.001
logsource:
    product: windows
    category: process_creation
detection:
    selection_img:
        - OriginalFileName:
              - 'powershell_ise.exe'
              - 'PowerShell.EXE'
              - 'pwsh.dll'
        - Image|endswith:
              - '\powershell_ise.exe'
              - '\powershell.exe'
              - '\pwsh.exe'
    selection_option:
        CommandLine|contains:
            - '-executionpolicy '
            - ' -ep '
            - ' -exec '
    selection_level:
        CommandLine|contains:
            - 'Bypass'
            - 'Unrestricted'
    filter_main_powershell_core:
        ParentImage:
            - 'C:\Windows\SysWOW64\msiexec.exe'
            - 'C:\Windows\System32\msiexec.exe'
        CommandLine|contains:
            - '-NoProfile -ExecutionPolicy Bypass -File "C:\Program Files\PowerShell\7\'
            - '-NoProfile -ExecutionPolicy Bypass -File "C:\Program Files (x86)\PowerShell\7\'
    filter_optional_avast:
        ParentImage|contains:
            - 'C:\Program Files\Avast Software\Avast\'
            - 'C:\Program Files (x86)\Avast Software\Avast\'
            - '\instup.exe'
        CommandLine|contains:
            - '-ExecutionPolicy ByPass -File "C:\Program Files\Avast Software\Avast'
            - '-ExecutionPolicy ByPass -File "C:\Program Files (x86)\Avast Software\Avast\'
    condition: all of selection_* and not 1 of filter_main_* and not 1 of filter_optional_*
falsepositives:
    - Administrator scripts
level: medium

Stages and Predicates

Stage 0: `condition`

all of selection_* and not 1 of filter_main_* and not 1 of filter_optional_*

Stage 1: `selection_img`

selection_img:
    - OriginalFileName:
          - 'powershell_ise.exe'
          - 'PowerShell.EXE'
          - 'pwsh.dll'
    - Image|endswith:
          - '\powershell_ise.exe'
          - '\powershell.exe'
          - '\pwsh.exe'

Stage 2: `selection_option`

selection_option:
    CommandLine|contains:
        - '-executionpolicy '
        - ' -ep '
        - ' -exec '

Stage 3: `selection_level`

selection_level:
    CommandLine|contains:
        - 'Bypass'
        - 'Unrestricted'

Stage 4: `not filter_main_powershell_core`

filter_main_powershell_core:
    ParentImage:
        - 'C:\Windows\SysWOW64\msiexec.exe'
        - 'C:\Windows\System32\msiexec.exe'
    CommandLine|contains:
        - '-NoProfile -ExecutionPolicy Bypass -File "C:\Program Files\PowerShell\7\'
        - '-NoProfile -ExecutionPolicy Bypass -File "C:\Program Files (x86)\PowerShell\7\'

Stage 5: `not filter_optional_avast`

filter_optional_avast:
    ParentImage|contains:
        - 'C:\Program Files\Avast Software\Avast\'
        - 'C:\Program Files (x86)\Avast Software\Avast\'
        - '\instup.exe'
    CommandLine|contains:
        - '-ExecutionPolicy ByPass -File "C:\Program Files\Avast Software\Avast'
        - '-ExecutionPolicy ByPass -File "C:\Program Files (x86)\Avast Software\Avast\'

Exclusions

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

Field	Kind	Excluded values
`CommandLine`	match	`-NoProfile -ExecutionPolicy Bypass -File "C:\Program Files (x86)\PowerShell\7\`
`CommandLine`	match	`-NoProfile -ExecutionPolicy Bypass -File "C:\Program Files\PowerShell\7\`
`ParentImage`	eq	`C:\Windows\SysWOW64\msiexec.exe`
`ParentImage`	eq	`C:\Windows\System32\msiexec.exe`
`CommandLine`	match	`-ExecutionPolicy ByPass -File "C:\Program Files (x86)\Avast Software\Avast\`
`CommandLine`	match	`-ExecutionPolicy ByPass -File "C:\Program Files\Avast Software\Avast`
`ParentImage`	match	`C:\Program Files (x86)\Avast Software\Avast\`
`ParentImage`	match	`C:\Program Files\Avast Software\Avast\`
`ParentImage`	match	`\instup.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
`CommandLine`	match	`-ep` `-exec` `-executionpolicy` `Bypass` corpus 6 (sigma 6) `Unrestricted` corpus 2 (sigma 2)
`Image`	ends_with	`\powershell.exe` corpus 182 (sigma 182) `\powershell_ise.exe` corpus 41 (sigma 41) `\pwsh.exe` corpus 168 (sigma 168)
`OriginalFileName`	eq	`PowerShell.EXE` corpus 120 (sigma 84, splunk 30, elastic 6) `powershell_ise.exe` corpus 51 (splunk 30, sigma 18, elastic 3) `pwsh.dll` corpus 112 (sigma 79, splunk 30, elastic 3)

`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)

Change PowerShell Policies to an Insecure Level

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection_img`

Stage 2: `selection_option`

Stage 3: `selection_level`

Stage 4: `not filter_main_powershell_core`

Stage 5: `not filter_optional_avast`

Exclusions

Indicators

Keyboard shortcuts

Search operators

Change PowerShell Policies to an Insecure Level

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection_img

Stage 2: selection_option

Stage 3: selection_level

Stage 4: not filter_main_powershell_core

Stage 5: not filter_optional_avast

Exclusions

Indicators

Stage 0: `condition`

Stage 1: `selection_img`

Stage 2: `selection_option`

Stage 3: `selection_level`

Stage 4: `not filter_main_powershell_core`

Stage 5: `not filter_optional_avast`