Scheduled persistent task with SYSTEM privileges creation

Status: experimental
Severity: high
Log source: product windows, category process_creation
Author: mdecrevoisier
Source: github.com/mdecrevoisier/SIGMA-detection-rules

Detects scenarios where an attacker creates a privileged task to establish persistence.

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1053.005` Scheduled Task/Job: Scheduled Task

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: Scheduled persistent task with SYSTEM privileges creation
description: Detects scenarios where an attacker creates a privileged task to establish persistence.
references:
- https://github.com/mdecrevoisier/EVTX-to-MITRE-Attack/tree/master/TA0002-Execution/T1053.005-Scheduled%20Task
- https://www.ired.team/offensive-security/persistence/t1053-schtask
- https://pentestlab.blog/2019/11/04/persistence-scheduled-tasks/
- http://www.fuzzysecurity.com/tutorials/19.html
- https://nasbench.medium.com/a-deep-dive-into-windows-scheduled-tasks-and-the-processes-running-them-218d1eed4cce
- https://posts.specterops.io/abstracting-scheduled-tasks-3b6451f6a1c5
- https://www.darkoperator.com/blog/2009/4/11/abusing-the-scheduler-with-meterpreter.html
- https://blog.menasec.net/2019/03/threat-hunting-25-scheduled-tasks-for.html
- https://strontic.github.io/xcyclopedia/library/schtasks.exe-5BD86A7193D38880F339D4AFB1F9B63A.html
- https://redcanary.com/blog/microsoft-exchange-attacks/
- https://nasbench.medium.com/behind-the-detection-schtasks-eb67a33a8710
- https://www.linkedin.com/pulse/lolbin-attacks-scheduled-tasks-t1503005-how-detect-them-v%C3%B6gele
tags:
- attack.execution
- attack.t1053.005
author: mdecrevoisier
status: experimental
logsource:
  product: windows
  category: process_creation
detection: # Full command: "schtasks /create /sc minute /mo 1 /tn eviltask /tr C:\tools\shell.cmd /ru SYSTEM"
  selection:
    NewProcessName|endswith: \schtasks.exe
    CommandLine|contains|all:
      - create
      #- ru      # Run with privileges from user X
      #- SYSTEM  # Run with SYSTEM privileges
      - tr      # Program, path or command to run
      - sc      # Run task every X minutes
  condition: selection
falsepositives:
- Administrator
level: high

# Extract ID 4698
# <?xml version="1.0" encoding="UTF-16"?> <Task version="1.2" xmlns="http://schemas.microsoft.com/windows/2004/02/mit/task"> <RegistrationInfo> <Date>2021-04-21T13:30:00</Date> <Author>demo\user1</Author> <URI>\eviltask</URI> </RegistrationInfo> <Triggers> <TimeTrigger> <Repetition> <Interval>PT1M</Interval> <StopAtDurationEnd>false</StopAtDurationEnd> </Repetition> <StartBoundary>2021-04-21T13:30:00</StartBoundary> <Enabled>true</Enabled> </TimeTrigger> </Triggers> <Settings> <MultipleInstancesPolicy>IgnoreNew</MultipleInstancesPolicy> <DisallowStartIfOnBatteries>true</DisallowStartIfOnBatteries> <StopIfGoingOnBatteries>true</StopIfGoingOnBatteries> <AllowHardTerminate>true</AllowHardTerminate> <StartWhenAvailable>false</StartWhenAvailable> <RunOnlyIfNetworkAvailable>false</RunOnlyIfNetworkAvailable> <IdleSettings> <Duration>PT10M</Duration> <WaitTimeout>PT1H</WaitTimeout> <StopOnIdleEnd>true</StopOnIdleEnd> <RestartOnIdle>false</RestartOnIdle> </IdleSettings> <AllowStartOnDemand>true</AllowStartOnDemand> <Enabled>true</Enabled> <Hidden>false</Hidden> <RunOnlyIfIdle>false</RunOnlyIfIdle> <WakeToRun>false</WakeToRun> <ExecutionTimeLimit>PT72H</ExecutionTimeLimit> <Priority>7</Priority> </Settings> <Actions Context="Author"> <Exec> <Command>C:\tools\shell.cmd</Command> </Exec> </Actions> <Principals> <Principal id="Author"> <UserId>S-1-5-18</UserId> <RunLevel>LeastPrivilege</RunLevel> </Principal> </Principals> </Task>

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
  NewProcessName|endswith: \schtasks.exe
  CommandLine|contains|all:
    - create
    - tr
    - sc

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	`create` corpus 24 (sigma 17, splunk 7) `sc` corpus 6 (sigma 6) `tr`
`NewProcessName`	ends_with	`\schtasks.exe` corpus 56 (sigma 56)

`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)

Scheduled persistent task with SYSTEM privileges creation

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection`

Indicators

Keyboard shortcuts

Search operators

Scheduled persistent task with SYSTEM privileges creation

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection

Indicators

Stage 0: `condition`

Stage 1: `selection`