Potential Emotet Activity

Status: stable
Severity: high
Log source: product windows, category process_creation
Author: Florian Roth (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects all Emotet like process executions that are not covered by the more generic rules

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1059.001` Command and Scripting Interpreter: PowerShell
Stealth	`T1027` Obfuscated Files or Information

Event coverage

Provider	Event	Title
Sysmon	Event ID 1	Process creation
Security-Auditing	Event ID 4688	A new process has been created.

Rule body yaml

title: Potential Emotet Activity
id: d02e8cf5-6099-48cf-9bfc-1eec2d0c7b18
status: stable
description: Detects all Emotet like process executions that are not covered by the more generic rules
references:
    - https://app.any.run/tasks/e13ab713-64cf-4b23-ad93-6dceaa5429ac/
    - https://app.any.run/tasks/81f3c28c-c686-425d-8a2b-a98198d244e1/
    - https://app.any.run/tasks/97f875e8-0e08-4328-815f-055e971ba754/
    - https://app.any.run/tasks/84fc9b4a-ea2b-47b1-8aa6-9014402dfb56/
author: Florian Roth (Nextron Systems)
date: 2019-09-30
modified: 2023-02-04
tags:
    - attack.execution
    - attack.stealth
    - attack.t1059.001
    - attack.t1027
    - detection.emerging-threats
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        CommandLine|contains:
            - ' -e* PAA'
            - 'JABlAG4AdgA6AHUAcwBlAHIAcAByAG8AZgBpAGwAZQ' # $env:userprofile
            - 'QAZQBuAHYAOgB1AHMAZQByAHAAcgBvAGYAaQBsAGUA' # $env:userprofile
            - 'kAGUAbgB2ADoAdQBzAGUAcgBwAHIAbwBmAGkAbABlA' # $env:userprofile
            - 'IgAoACcAKgAnACkAOwAkA' # "('*');$
            - 'IAKAAnACoAJwApADsAJA' # "('*');$
            - 'iACgAJwAqACcAKQA7ACQA' # "('*');$
            - 'JABGAGwAeAByAGgAYwBmAGQ'
            - 'PQAkAGUAbgB2ADoAdABlAG0AcAArACgA' # =$env:temp+(
            - '0AJABlAG4AdgA6AHQAZQBtAHAAKwAoA' # =$env:temp+(
            - '9ACQAZQBuAHYAOgB0AGUAbQBwACsAKA' # =$env:temp+(
    filter:
        CommandLine|contains:
            - 'fAAgAEMAbwBuAHYAZQByAHQAVABvAC0ASgBzAG8AbgAgAC0ARQByAHIAbwByAEEAYwB0AGkAbwBuACAAUwBpAGwAZQBuAHQAbAB5AEMAbwBuAHQAaQBuAHUAZQ'
            - 'wAIABDAG8AbgB2AGUAcgB0AFQAbwAtAEoAcwBvAG4AIAAtAEUAcgByAG8AcgBBAGMAdABpAG8AbgAgAFMAaQBsAGUAbgB0AGwAeQBDAG8AbgB0AGkAbgB1AGUA'
            - '8ACAAQwBvAG4AdgBlAHIAdABUAG8ALQBKAHMAbwBuACAALQBFAHIAcgBvAHIAQQBjAHQAaQBvAG4AIABTAGkAbABlAG4AdABsAHkAQwBvAG4AdABpAG4AdQBlA'
    condition: selection and not filter
falsepositives:
    - Unlikely
level: high

Stages and Predicates

Stage 0: `condition`

selection and not filter

Stage 1: `selection`

selection:
    CommandLine|contains:
        - ' -e* PAA'
        - 'JABlAG4AdgA6AHUAcwBlAHIAcAByAG8AZgBpAGwAZQ'
        - 'QAZQBuAHYAOgB1AHMAZQByAHAAcgBvAGYAaQBsAGUA'
        - 'kAGUAbgB2ADoAdQBzAGUAcgBwAHIAbwBmAGkAbABlA'
        - 'IgAoACcAKgAnACkAOwAkA'
        - 'IAKAAnACoAJwApADsAJA'
        - 'iACgAJwAqACcAKQA7ACQA'
        - 'JABGAGwAeAByAGgAYwBmAGQ'
        - 'PQAkAGUAbgB2ADoAdABlAG0AcAArACgA'
        - '0AJABlAG4AdgA6AHQAZQBtAHAAKwAoA'
        - '9ACQAZQBuAHYAOgB0AGUAbQBwACsAKA'

Stage 2: `not filter`

filter:
    CommandLine|contains:
        - 'fAAgAEMAbwBuAHYAZQByAHQAVABvAC0ASgBzAG8AbgAgAC0ARQByAHIAbwByAEEAYwB0AGkAbwBuACAAUwBpAGwAZQBuAHQAbAB5AEMAbwBuAHQAaQBuAHUAZQ'
        - 'wAIABDAG8AbgB2AGUAcgB0AFQAbwAtAEoAcwBvAG4AIAAtAEUAcgByAG8AcgBBAGMAdABpAG8AbgAgAFMAaQBsAGUAbgB0AGwAeQBDAG8AbgB0AGkAbgB1AGUA'
        - '8ACAAQwBvAG4AdgBlAHIAdABUAG8ALQBKAHMAbwBuACAALQBFAHIAcgBvAHIAQQBjAHQAaQBvAG4AIABTAGkAbABlAG4AdABsAHkAQwBvAG4AdABpAG4AdQBlA'

Exclusions

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

Field	Kind	Excluded values
`CommandLine`	match	`8ACAAQwBvAG4AdgBlAHIAdABUAG8ALQBKAHMAbwBuACAALQBFAHIAcgBvAHIAQQBjAHQAaQBvAG4AIABTAGkAbABlAG4AdABsAHkAQwBvAG4AdABpAG4AdQBlA`
`CommandLine`	match	`fAAgAEMAbwBuAHYAZQByAHQAVABvAC0ASgBzAG8AbgAgAC0ARQByAHIAbwByAEEAYwB0AGkAbwBuACAAUwBpAGwAZQBuAHQAbAB5AEMAbwBuAHQAaQBuAHUAZQ`
`CommandLine`	match	`wAIABDAG8AbgB2AGUAcgB0AFQAbwAtAEoAcwBvAG4AIAAtAEUAcgByAG8AcgBBAGMAdABpAG8AbgAgAFMAaQBsAGUAbgB0AGwAeQBDAG8AbgB0AGkAbgB1AGUA`

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	`-e* PAA` corpus 2 (sigma 2) `0AJABlAG4AdgA6AHQAZQBtAHAAKwAoA` `9ACQAZQBuAHYAOgB0AGUAbQBwACsAKA` `IAKAAnACoAJwApADsAJA` `IgAoACcAKgAnACkAOwAkA` `JABGAGwAeAByAGgAYwBmAGQ` `JABlAG4AdgA6AHUAcwBlAHIAcAByAG8AZgBpAGwAZQ` `PQAkAGUAbgB2ADoAdABlAG0AcAArACgA` `QAZQBuAHYAOgB1AHMAZQByAHAAcgBvAGYAaQBsAGUA` `iACgAJwAqACcAKQA7ACQA` `kAGUAbgB2ADoAdQBzAGUAcgBwAHIAbwBmAGkAbABlA`

`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 Emotet Activity

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection`

Stage 2: `not filter`

Exclusions

Indicators

Keyboard shortcuts

Search operators

Potential Emotet Activity

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection

Stage 2: not filter

Exclusions

Indicators

Stage 0: `condition`

Stage 1: `selection`

Stage 2: `not filter`