Suspicious Scheduled Task Creation via Masqueraded XML File

Status: test
Severity: medium
Log source: product windows, category process_creation
Author: Swachchhanda Shrawan Poudel, Elastic (idea)
Source: github.com/SigmaHQ/sigma

Detects the creation of a scheduled task using the "-XML" flag with a file without the '.xml' extension. This behavior could be indicative of potential defense evasion attempt during persistence

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
Stealth	`T1036.005` Masquerading: Match Legitimate Resource Name or Location

Event coverage

Provider	Event	Title
Sysmon	Event ID 1	Process creation

Rule body yaml

title: Suspicious Scheduled Task Creation via Masqueraded XML File
id: dd2a821e-3b07-4d3b-a9ac-929fe4c6ca0c
status: test
description: Detects the creation of a scheduled task using the "-XML" flag with a file without the '.xml' extension. This behavior could be indicative of potential defense evasion attempt during persistence
references:
    - https://learn.microsoft.com/en-us/windows/win32/taskschd/daily-trigger-example--xml-
    - https://github.com/elastic/protections-artifacts/blob/084067123d3328a823b1c3fdde305b694275c794/behavior/rules/persistence_suspicious_scheduled_task_creation_via_masqueraded_xml_file.toml
author: Swachchhanda Shrawan Poudel, Elastic (idea)
date: 2023-04-20
modified: 2024-12-01
tags:
    - attack.privilege-escalation
    - attack.execution
    - attack.persistence
    - attack.stealth
    - attack.t1036.005
    - attack.t1053.005
logsource:
    product: windows
    category: process_creation
detection:
    selection_img:
        - Image|endswith: '\schtasks.exe'
        - OriginalFileName: 'schtasks.exe'
    selection_cli_create:
        CommandLine|contains:
            - '/create'
            - '-create'
    selection_cli_xml:
        CommandLine|contains:
            - '/xml'
            - '-xml'
    filter_main_extension_xml:
        CommandLine|contains: '.xml'
    filter_main_system_process:
        IntegrityLevel:
            - 'System'
            - 'S-1-16-16384'
    filter_main_rundll32:
        ParentImage|endswith: '\rundll32.exe'
        ParentCommandLine|contains|all:
            - ':\WINDOWS\Installer\MSI'
            - '.tmp,zzzzInvokeManagedCustomActionOutOfProc'
    filter_optional_third_party:
        ParentImage|endswith:
            # Consider removing any tools that you don't use to avoid blind spots
            - ':\ProgramData\OEM\UpgradeTool\CareCenter_*\BUnzip\Setup_msi.exe'
            - ':\Program Files\Axis Communications\AXIS Camera Station\SetupActions.exe'
            - ':\Program Files\Axis Communications\AXIS Device Manager\AdmSetupActions.exe'
            - ':\Program Files (x86)\Zemana\AntiMalware\AntiMalware.exe'
            - ':\Program Files\Dell\SupportAssist\pcdrcui.exe'
    condition: all of selection_* and not 1 of filter_main_* and not 1 of filter_optional_*
falsepositives:
    - Unknown
level: medium

Stages and Predicates

Stage 0: `condition`

all of selection_* and not 1 of filter_main_* and not 1 of filter_optional_*

Stage 1: `selection_img`

selection_img:
    - Image|endswith: '\schtasks.exe'
    - OriginalFileName: 'schtasks.exe'

Stage 2: `selection_cli_create`

selection_cli_create:
    CommandLine|contains:
        - '/create'
        - '-create'

Stage 3: `selection_cli_xml`

selection_cli_xml:
    CommandLine|contains:
        - '/xml'
        - '-xml'

Stage 4: `not filter_main_*`

filter_main_extension_xml:
    CommandLine|contains: '.xml'
filter_main_system_process:
    IntegrityLevel:
        - 'System'
        - 'S-1-16-16384'
filter_main_rundll32:
    ParentImage|endswith: '\rundll32.exe'
    ParentCommandLine|contains|all:
        - ':\WINDOWS\Installer\MSI'
        - '.tmp,zzzzInvokeManagedCustomActionOutOfProc'

Stage 5: `not filter_optional_third_party`

filter_optional_third_party:
    ParentImage|endswith:
        - ':\ProgramData\OEM\UpgradeTool\CareCenter_*\BUnzip\Setup_msi.exe'
        - ':\Program Files\Axis Communications\AXIS Camera Station\SetupActions.exe'
        - ':\Program Files\Axis Communications\AXIS Device Manager\AdmSetupActions.exe'
        - ':\Program Files (x86)\Zemana\AntiMalware\AntiMalware.exe'
        - ':\Program Files\Dell\SupportAssist\pcdrcui.exe'

Exclusions

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

Field	Kind	Excluded values
`ParentCommandLine`	match	`.tmp,zzzzInvokeManagedCustomActionOutOfProc`
`ParentCommandLine`	match	`:\WINDOWS\Installer\MSI`
`ParentImage`	ends_with	`\rundll32.exe`
`CommandLine`	match	`.xml`
`IntegrityLevel`	eq	`S-1-16-16384`
`IntegrityLevel`	eq	`System`
`ParentImage`	ends_with	`:\Program Files (x86)\Zemana\AntiMalware\AntiMalware.exe`
`ParentImage`	ends_with	`:\Program Files\Axis Communications\AXIS Camera Station\SetupActions.exe`
`ParentImage`	ends_with	`:\Program Files\Axis Communications\AXIS Device Manager\AdmSetupActions.exe`
`ParentImage`	ends_with	`:\Program Files\Dell\SupportAssist\pcdrcui.exe`
`ParentImage`	ends_with	`:\ProgramData\OEM\UpgradeTool\CareCenter_*\BUnzip\Setup_msi.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	`-create` corpus 2 (sigma 1, splunk 1) `-xml` `/create` corpus 9 (sigma 6, splunk 2, kusto 1) `/xml`
`Image`	ends_with	`\schtasks.exe` corpus 56 (sigma 56)
`OriginalFileName`	eq	`schtasks.exe` corpus 23 (sigma 18, splunk 4, elastic 1)

`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)

Suspicious Scheduled Task Creation via Masqueraded XML File

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection_img`

Stage 2: `selection_cli_create`

Stage 3: `selection_cli_xml`

Stage 4: `not filter_main_*`

Stage 5: `not filter_optional_third_party`

Exclusions

Indicators

Keyboard shortcuts

Search operators

Suspicious Scheduled Task Creation via Masqueraded XML File

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection_img

Stage 2: selection_cli_create

Stage 3: selection_cli_xml

Stage 4: not filter_main_*

Stage 5: not filter_optional_third_party

Exclusions

Indicators

Stage 0: `condition`

Stage 1: `selection_img`

Stage 2: `selection_cli_create`

Stage 3: `selection_cli_xml`

Stage 4: `not filter_main_*`

Stage 5: `not filter_optional_third_party`