Schtasks Creation Or Modification With SYSTEM Privileges

Status: test
Severity: high
Log source: product windows, category process_creation
Author: Nasreddine Bencherchali (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects the creation or update of a scheduled task to run with "NT AUTHORITY\SYSTEM" privileges

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1053.005` Scheduled Task/Job: Scheduled Task
Persistence	`T1053.005` Scheduled Task/Job: Scheduled Task
Privilege Escalation	`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: Schtasks Creation Or Modification With SYSTEM Privileges
id: 89ca78fd-b37c-4310-b3d3-81a023f83936
status: test
description: Detects the creation or update of a scheduled task to run with "NT AUTHORITY\SYSTEM" privileges
references:
    - https://www.elastic.co/security-labs/exploring-the-qbot-attack-pattern
    - https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/schtasks
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-07-28
modified: 2025-02-15
tags:
    - attack.privilege-escalation
    - attack.execution
    - attack.persistence
    - attack.t1053.005
logsource:
    product: windows
    category: process_creation
detection:
    selection_root:
        Image|endswith: '\schtasks.exe'
        CommandLine|contains:
            - ' /change '
            - ' /create '
    selection_run:
        CommandLine|contains: '/ru '
    selection_user:
        CommandLine|contains:
            - 'NT AUT' # This covers the usual NT AUTHORITY\SYSTEM
            - ' SYSTEM ' # SYSTEM is a valid value for schtasks hence it gets it's own value with space
    filter_optional_teamviewer:
        # FP from test set in SIGMA
        # Cannot use ParentImage on all OSes for 4688 events
        # ParentImage|contains|all:
        #     - '\AppData\Local\Temp\'
        #     - 'TeamViewer_.exe'
        Image|endswith: '\schtasks.exe'
        CommandLine|contains|all:
            - '/TN TVInstallRestore'
            - '\TeamViewer_.exe'
    filter_optional_office:
        CommandLine|contains|all:
            # https://answers.microsoft.com/en-us/msoffice/forum/all/office-15-subscription-heartbeat-task-created-on/43ab5e53-a9fb-47c6-8c14-44889974b9ff
            - 'Subscription Heartbeat'
            - '\HeartbeatConfig.xml'
            - '\Microsoft Shared\OFFICE'
    filter_optional_avira:
        CommandLine|contains:
            - '/Create /F /RU System /SC WEEKLY /TN AviraSystemSpeedupVerify /TR '
            - ':\Program Files (x86)\Avira\System Speedup\setup\avira_speedup_setup.exe'
            - '/VERIFY /VERYSILENT /NOSTART /NODOTNET /NORESTART" /RL HIGHEST'
    condition: all of selection_* and not 1 of filter_optional_*
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: `condition`

all of selection_* and not 1 of filter_optional_*

Stage 1: `selection_root`

selection_root:
    Image|endswith: '\schtasks.exe'
    CommandLine|contains:
        - ' /change '
        - ' /create '

Stage 2: `selection_run`

selection_run:
    CommandLine|contains: '/ru '

Stage 3: `selection_user`

selection_user:
    CommandLine|contains:
        - 'NT AUT'
        - ' SYSTEM '

Stage 4: `not filter_optional_*`

filter_optional_teamviewer:
    Image|endswith: '\schtasks.exe'
    CommandLine|contains|all:
        - '/TN TVInstallRestore'
        - '\TeamViewer_.exe'
filter_optional_office:
    CommandLine|contains|all:
        - 'Subscription Heartbeat'
        - '\HeartbeatConfig.xml'
        - '\Microsoft Shared\OFFICE'
filter_optional_avira:
    CommandLine|contains:
        - '/Create /F /RU System /SC WEEKLY /TN AviraSystemSpeedupVerify /TR '
        - ':\Program Files (x86)\Avira\System Speedup\setup\avira_speedup_setup.exe'
        - '/VERIFY /VERYSILENT /NOSTART /NODOTNET /NORESTART" /RL HIGHEST'

Exclusions

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

Field	Kind	Excluded values
`CommandLine`	match	`/TN TVInstallRestore`
`CommandLine`	match	`\TeamViewer_.exe`
`Image`	ends_with	`\schtasks.exe`
`CommandLine`	match	`Subscription Heartbeat`
`CommandLine`	match	`\HeartbeatConfig.xml`
`CommandLine`	match	`\Microsoft Shared\OFFICE`
`CommandLine`	match	`/Create /F /RU System /SC WEEKLY /TN AviraSystemSpeedupVerify /TR`
`CommandLine`	match	`/VERIFY /VERYSILENT /NOSTART /NODOTNET /NORESTART" /RL HIGHEST`
`CommandLine`	match	`:\Program Files (x86)\Avira\System Speedup\setup\avira_speedup_setup.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	`/change` corpus 3 (sigma 3) `/create` corpus 15 (sigma 15) `SYSTEM` corpus 2 (sigma 2) `/ru` corpus 2 (sigma 1, splunk 1) `NT AUT` corpus 3 (sigma 3)
`Image`	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)

Schtasks Creation Or Modification With SYSTEM Privileges

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection_root`

Stage 2: `selection_run`

Stage 3: `selection_user`

Stage 4: `not filter_optional_*`

Exclusions

Indicators

Keyboard shortcuts

Search operators

Schtasks Creation Or Modification With SYSTEM Privileges

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection_root

Stage 2: selection_run

Stage 3: selection_user

Stage 4: not filter_optional_*

Exclusions

Indicators

Stage 0: `condition`

Stage 1: `selection_root`

Stage 2: `selection_run`

Stage 3: `selection_user`

Stage 4: `not filter_optional_*`