Tasks Folder Evasion

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

The Tasks folder in system32 and syswow64 are globally writable paths. Adversaries can take advantage of this and load or influence any script hosts or ANY .NET Application in Tasks to load and execute a custom assembly into cscript, wscript, regsvr32, mshta, eventvwr

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1574.001` Hijack Execution Flow: DLL
Stealth	`T1574.001` Hijack Execution Flow: DLL

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: Tasks Folder Evasion
id: cc4e02ba-9c06-48e2-b09e-2500cace9ae0
status: test
description: |
    The Tasks folder in system32 and syswow64 are globally writable paths.
    Adversaries can take advantage of this and load or influence any script hosts or ANY .NET Application
    in Tasks to load and execute a custom assembly into cscript, wscript, regsvr32, mshta, eventvwr
references:
    - https://twitter.com/subTee/status/1216465628946563073
    - https://gist.github.com/am0nsec/8378da08f848424e4ab0cc5b317fdd26
author: Sreeman
date: 2020-01-13
modified: 2022-12-25
tags:
    - attack.privilege-escalation
    - attack.persistence
    - attack.execution
    - attack.stealth
    - attack.t1574.001
logsource:
    product: windows
    category: process_creation
detection:
    selection1:
        CommandLine|contains:
            - 'echo '
            - 'copy '
            - 'type '
            - 'file createnew'
    selection2:
        CommandLine|contains:
            - ' C:\Windows\System32\Tasks\'
            - ' C:\Windows\SysWow64\Tasks\'
    condition: all of selection*
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: `condition`

all of selection*

Stage 1: `selection1`

selection1:
    CommandLine|contains:
        - 'echo '
        - 'copy '
        - 'type '
        - 'file createnew'

Stage 2: `selection2`

selection2:
    CommandLine|contains:
        - ' C:\Windows\System32\Tasks\'
        - ' C:\Windows\SysWow64\Tasks\'

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	`C:\Windows\SysWow64\Tasks\` `C:\Windows\System32\Tasks\` `copy` corpus 12 (sigma 11, chronicle 1) `echo` corpus 4 (sigma 2, elastic 2) `file createnew` corpus 2 (sigma 2) `type` corpus 6 (sigma 6)

`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)

Tasks Folder Evasion

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection1`

Stage 2: `selection2`

Indicators

Keyboard shortcuts

Search operators

Tasks Folder Evasion

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection1

Stage 2: selection2

Indicators

Stage 0: `condition`

Stage 1: `selection1`

Stage 2: `selection2`