Forest Blizzard APT - Process Creation Activity

Status: experimental
Severity: high
Author: Nasreddine Bencherchali (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects the execution of specific processes and command line combination. These were seen being created by Forest Blizzard as described by MSFT.

Event coverage

Provider	Event	Title
Sysmon	Event ID 1	Process creation

Rule body yaml

title: Forest Blizzard APT - Process Creation Activity
id: 07db928c-8632-488e-ac7d-3db847489175
status: experimental
description: |
    Detects the execution of specific processes and command line combination.
    These were seen being created by Forest Blizzard as described by MSFT.
references:
    - https://www.microsoft.com/en-us/security/blog/2024/04/22/analyzing-forest-blizzards-custom-post-compromise-tool-for-exploiting-cve-2022-38028-to-obtain-credentials/
author: Nasreddine Bencherchali (Nextron Systems)
date: 2024-04-23
modified: 2025-01-22
tags:
    - attack.execution
    - detection.emerging-threats
    - attack.stealth
logsource:
    category: process_creation
    product: windows
detection:
    selection_hashes:
        Hashes|contains:
            - 'SHA256=6b311c0a977d21e772ac4e99762234da852bbf84293386fbe78622a96c0b052f'
            - 'SHA256=c60ead92cd376b689d1b4450f2578b36ea0bf64f3963cfa5546279fa4424c2a5'
    selection_schtasks_create:
        Image|endswith: '\schtasks.exe'
        CommandLine|contains|all:
            - 'Create'
            - '/RU'
            - 'SYSTEM'
            - '\Microsoft\Windows\WinSrv'
        CommandLine|contains:
            - 'servtask.bat'
            - 'execute.bat'
            - 'doit.bat'
    selection_schtasks_delete:
        Image|endswith: '\schtasks.exe'
        CommandLine|contains|all:
            - 'Delete'
            - '/F '
            - '\Microsoft\Windows\WinSrv'
    selection_powershell:
        CommandLine|contains|all:
            - 'Get-ChildItem'
            - '.save'
            - 'Compress-Archive -DestinationPath C:\ProgramData\'
    condition: 1 of selection_*
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: `condition`

1 of selection_*

Stage 1: `selection_hashes`

selection_hashes:
    Hashes|contains:
        - 'SHA256=6b311c0a977d21e772ac4e99762234da852bbf84293386fbe78622a96c0b052f'
        - 'SHA256=c60ead92cd376b689d1b4450f2578b36ea0bf64f3963cfa5546279fa4424c2a5'

Stage 2: `selection_schtasks_create`

selection_schtasks_create:
    Image|endswith: '\schtasks.exe'
    CommandLine|contains|all:
        - 'Create'
        - '/RU'
        - 'SYSTEM'
        - '\Microsoft\Windows\WinSrv'
    CommandLine|contains:
        - 'servtask.bat'
        - 'execute.bat'
        - 'doit.bat'

Stage 3: `selection_schtasks_delete`

selection_schtasks_delete:
    Image|endswith: '\schtasks.exe'
    CommandLine|contains|all:
        - 'Delete'
        - '/F '
        - '\Microsoft\Windows\WinSrv'

Stage 4: `selection_powershell`

selection_powershell:
    CommandLine|contains|all:
        - 'Get-ChildItem'
        - '.save'
        - 'Compress-Archive -DestinationPath C:\ProgramData\'

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	`.save` `/F` corpus 3 (sigma 3) `/RU` corpus 3 (sigma 3) `Compress-Archive -DestinationPath C:\ProgramData\` `Create` corpus 23 (sigma 16, splunk 7) `Delete` corpus 22 (sigma 15, splunk 6, kusto 1) `Get-ChildItem` `SYSTEM` corpus 2 (sigma 1, splunk 1) `\Microsoft\Windows\WinSrv` `doit.bat` `execute.bat` `servtask.bat`
`Hashes`	match	`SHA256=6b311c0a977d21e772ac4e99762234da852bbf84293386fbe78622a96c0b052f` `SHA256=c60ead92cd376b689d1b4450f2578b36ea0bf64f3963cfa5546279fa4424c2a5`
`Image`	ends_with	`\schtasks.exe` corpus 57 (sigma 57)

`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:`)
`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)

Forest Blizzard APT - Process Creation Activity

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection_hashes`

Stage 2: `selection_schtasks_create`

Stage 3: `selection_schtasks_delete`

Stage 4: `selection_powershell`

Indicators

Keyboard shortcuts

Search operators

Forest Blizzard APT - Process Creation Activity

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection_hashes

Stage 2: selection_schtasks_create

Stage 3: selection_schtasks_delete

Stage 4: selection_powershell

Indicators

Stage 0: `condition`

Stage 1: `selection_hashes`

Stage 2: `selection_schtasks_create`

Stage 3: `selection_schtasks_delete`

Stage 4: `selection_powershell`