COLDSTEEL RAT Cleanup Command Execution

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

Detects the creation of a "rundll32" process from the ColdSteel persistence service to initiate the cleanup command by calling one of its own exports. This functionality is not present in "MileStone2017" and some "MileStone2016" samples

MITRE ATT&CK coverage

Tactic	Techniques
Persistence	No specific technique
Stealth	No specific technique

Event coverage

Provider	Event	Title
Sysmon	Event ID 1	Process creation

Rule body yaml

title: COLDSTEEL RAT Cleanup Command Execution
id: 88516f06-ebe0-47ad-858e-ae9fd060ddea
status: test
description: Detects the creation of a "rundll32" process from the ColdSteel persistence service to initiate the cleanup command by calling one of its own exports. This functionality is not present in "MileStone2017" and some "MileStone2016" samples
references:
    - https://www.ncsc.gov.uk/static-assets/documents/malware-analysis-reports/cold-steel/NCSC-MAR-Cold-Steel.pdf
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-04-30
tags:
    - attack.persistence
    - detection.emerging-threats
    - attack.stealth
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith: '\svchost.exe'
        ParentCommandLine|contains:
            - ' -k msupdate'
            - ' -k msupdate2'
            - ' -k alg'
        Image|endswith: '\rundll32.exe'
        CommandLine|contains:
            - 'UpdateDriverForPlugAndPlayDevicesW'
            - 'ServiceMain'
            - 'DiUninstallDevice'
    condition: selection
falsepositives:
    - Unlikely
level: critical

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    ParentImage|endswith: '\svchost.exe'
    ParentCommandLine|contains:
        - ' -k msupdate'
        - ' -k msupdate2'
        - ' -k alg'
    Image|endswith: '\rundll32.exe'
    CommandLine|contains:
        - 'UpdateDriverForPlugAndPlayDevicesW'
        - 'ServiceMain'
        - 'DiUninstallDevice'

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	`DiUninstallDevice` `ServiceMain` `UpdateDriverForPlugAndPlayDevicesW`
`Image`	ends_with	`\rundll32.exe` corpus 95 (sigma 95)
`ParentCommandLine`	match	`-k alg` `-k msupdate` `-k msupdate2`
`ParentImage`	ends_with	`\svchost.exe` corpus 14 (sigma 14)

`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)

COLDSTEEL RAT Cleanup Command Execution

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection`

Indicators

Keyboard shortcuts

Search operators

COLDSTEEL RAT Cleanup Command Execution

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`