Bad Opsec Powershell Code Artifacts

Status: test
Severity: critical
Log source: product windows, category ps_module
Author: ok @securonix invrep_de, oscd.community
Source: github.com/SigmaHQ/sigma

focuses on trivial artifacts observed in variants of prevalent offensive ps1 payloads, including Cobalt Strike Beacon, PoshC2, Powerview, Letmein, Empire, Powersploit, and other attack payloads that often undergo minimal changes by attackers due to bad opsec.

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.

Rule body yaml

title: Bad Opsec Powershell Code Artifacts
id: 8d31a8ce-46b5-4dd6-bdc3-680931f1db86
related:
    - id: 73e733cc-1ace-3212-a107-ff2523cc9fc3
      type: derived
status: test
description: |
    focuses on trivial artifacts observed in variants of prevalent offensive ps1 payloads, including
    Cobalt Strike Beacon, PoshC2, Powerview, Letmein, Empire, Powersploit, and other attack payloads
    that often undergo minimal changes by attackers due to bad opsec.
references:
    - https://newtonpaul.com/analysing-fileless-malware-cobalt-strike-beacon/
    - https://labs.sentinelone.com/top-tier-russian-organized-cybercrime-group-unveils-fileless-stealthy-powertrick-backdoor-for-high-value-targets/
    - https://www.mdeditor.tw/pl/pgRt
author: 'ok @securonix invrep_de, oscd.community'
date: 2020-10-09
modified: 2022-12-25
tags:
    - attack.execution
    - attack.t1059.001
logsource:
    product: windows
    category: ps_module
    definition: 0ad03ef1-f21b-4a79-8ce8-e6900c54b65b
detection:
    selection_4103:
        Payload|contains:
            - '$DoIt'
            - 'harmj0y'
            - 'mattifestation'
            - '_RastaMouse'
            - 'tifkin_'
            - '0xdeadbeef'
    condition: selection_4103
falsepositives:
    - 'Moderate-to-low; Despite the shorter length/lower entropy for some of these, because of high specificity, fp appears to be fairly limited in many environments.'
level: critical

Stages and Predicates

Stage 0: `condition`

selection_4103

Stage 1: `selection_4103`

selection_4103:
    Payload|contains:
        - '$DoIt'
        - 'harmj0y'
        - 'mattifestation'
        - '_RastaMouse'
        - 'tifkin_'
        - '0xdeadbeef'

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
`Payload`	match	`$DoIt` `0xdeadbeef` `_RastaMouse` `harmj0y` `mattifestation` `tifkin_`

`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)

Bad Opsec Powershell Code Artifacts

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection_4103`

Indicators

Keyboard shortcuts

Search operators

Bad Opsec Powershell Code Artifacts

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection_4103

Indicators

Stage 0: `condition`

Stage 1: `selection_4103`