Potentially Suspicious Rundll32 Activity

Status: test
Severity: medium
Log source: product windows, category process_creation
Author: juju4, Jonhnathan Ribeiro, oscd.community, Nasreddine Bencherchali (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects suspicious execution of rundll32, with specific calls to some DLLs with known LOLBIN functionalities

MITRE ATT&CK coverage

Tactic	Techniques
Stealth	`T1218.011` System Binary Proxy Execution: Rundll32

Event coverage

Provider	Event	Title
Sysmon	Event ID 1	Process creation

Rule body yaml

title: Potentially Suspicious Rundll32 Activity
id: e593cf51-88db-4ee1-b920-37e89012a3c9
status: test
description: Detects suspicious execution of rundll32, with specific calls to some DLLs with known LOLBIN functionalities
references:
    - http://www.hexacorn.com/blog/2017/05/01/running-programs-via-proxy-jumping-on-a-edr-bypass-trampoline/
    - https://twitter.com/Hexacorn/status/885258886428725250
    - https://gist.github.com/ryhanson/227229866af52e2d963cf941af135a52
    - https://twitter.com/nas_bench/status/1433344116071583746 # dfshim.dll,ShOpenVerbShortcut
    - https://twitter.com/eral4m/status/1479106975967240209 # scrobj.dll,GenerateTypeLib
    - https://twitter.com/eral4m/status/1479080793003671557 # shimgvw.dll,ImageView_Fullscreen
author: juju4, Jonhnathan Ribeiro, oscd.community, Nasreddine Bencherchali (Nextron Systems)
date: 2019-01-16
modified: 2023-05-17
tags:
    - attack.stealth
    - attack.t1218.011
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        - CommandLine|contains|all:
              - 'javascript:'
              - '.RegisterXLL'
        - CommandLine|contains|all:
              - 'url.dll'
              - 'OpenURL'
        - CommandLine|contains|all:
              - 'url.dll'
              - 'OpenURLA'
        - CommandLine|contains|all:
              - 'url.dll'
              - 'FileProtocolHandler'
        - CommandLine|contains|all:
              - 'zipfldr.dll'
              - 'RouteTheCall'
        - CommandLine|contains|all:
              - 'shell32.dll'
              - 'Control_RunDLL'
        - CommandLine|contains|all:
              - 'shell32.dll'
              - 'ShellExec_RunDLL'
        - CommandLine|contains|all:
              - 'mshtml.dll'
              - 'PrintHTML'
        - CommandLine|contains|all:
              - 'advpack.dll'
              - 'LaunchINFSection'
        - CommandLine|contains|all:
              - 'advpack.dll'
              - 'RegisterOCX'
        - CommandLine|contains|all:
              - 'ieadvpack.dll'
              - 'LaunchINFSection'
        - CommandLine|contains|all:
              - 'ieadvpack.dll'
              - 'RegisterOCX'
        - CommandLine|contains|all:
              - 'ieframe.dll'
              - 'OpenURL'
        - CommandLine|contains|all:
              - 'shdocvw.dll'
              - 'OpenURL'
        - CommandLine|contains|all:
              - 'syssetup.dll'
              - 'SetupInfObjectInstallAction'
        - CommandLine|contains|all:
              - 'setupapi.dll'
              - 'InstallHinfSection'
        - CommandLine|contains|all:
              - 'pcwutl.dll'
              - 'LaunchApplication'
        - CommandLine|contains|all:
              - 'dfshim.dll'
              - 'ShOpenVerbApplication'
        - CommandLine|contains|all:
              - 'dfshim.dll'
              - 'ShOpenVerbShortcut'
        - CommandLine|contains|all:
              - 'scrobj.dll'
              - 'GenerateTypeLib'
              - 'http'
        - CommandLine|contains|all:
              - 'shimgvw.dll'
              - 'ImageView_Fullscreen'
              - 'http'
        - CommandLine|contains|all:
              - 'comsvcs.dll'
              - 'MiniDump'
    filter_main_screensaver:
        CommandLine|contains: 'shell32.dll,Control_RunDLL desk.cpl,screensaver,@screensaver'
    filter_main_parent_cpl:  # Settings
        ParentImage: 'C:\Windows\System32\control.exe'
        ParentCommandLine|contains: '.cpl'
        CommandLine|contains|all:
            - 'Shell32.dll'
            - 'Control_RunDLL'
            - '.cpl'
    filter_main_startmenu:
        ParentImage: 'C:\Windows\System32\control.exe'
        CommandLine|startswith: '"C:\Windows\system32\rundll32.exe" Shell32.dll,Control_RunDLL "C:\Windows\System32\'
        CommandLine|endswith: '.cpl",'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - False positives depend on scripts and administrative tools used in the monitored environment
level: medium

Stages and Predicates

Stage 0: `condition`

selection and not 1 of filter_main_*

Stage 1: `selection`

selection:
    - CommandLine|contains|all:
          - 'javascript:'
          - '.RegisterXLL'
    - CommandLine|contains|all:
          - 'url.dll'
          - 'OpenURL'
    - CommandLine|contains|all:
          - 'url.dll'
          - 'OpenURLA'
    - CommandLine|contains|all:
          - 'url.dll'
          - 'FileProtocolHandler'
    - CommandLine|contains|all:
          - 'zipfldr.dll'
          - 'RouteTheCall'
    - CommandLine|contains|all:
          - 'shell32.dll'
          - 'Control_RunDLL'
    - CommandLine|contains|all:
          - 'shell32.dll'
          - 'ShellExec_RunDLL'
    - CommandLine|contains|all:
          - 'mshtml.dll'
          - 'PrintHTML'
    - CommandLine|contains|all:
          - 'advpack.dll'
          - 'LaunchINFSection'
    - CommandLine|contains|all:
          - 'advpack.dll'
          - 'RegisterOCX'
    - CommandLine|contains|all:
          - 'ieadvpack.dll'
          - 'LaunchINFSection'
    - CommandLine|contains|all:
          - 'ieadvpack.dll'
          - 'RegisterOCX'
    - CommandLine|contains|all:
          - 'ieframe.dll'
          - 'OpenURL'
    - CommandLine|contains|all:
          - 'shdocvw.dll'
          - 'OpenURL'
    - CommandLine|contains|all:
          - 'syssetup.dll'
          - 'SetupInfObjectInstallAction'
    - CommandLine|contains|all:
          - 'setupapi.dll'
          - 'InstallHinfSection'
    - CommandLine|contains|all:
          - 'pcwutl.dll'
          - 'LaunchApplication'
    - CommandLine|contains|all:
          - 'dfshim.dll'
          - 'ShOpenVerbApplication'
    - CommandLine|contains|all:
          - 'dfshim.dll'
          - 'ShOpenVerbShortcut'
    - CommandLine|contains|all:
          - 'scrobj.dll'
          - 'GenerateTypeLib'
          - 'http'
    - CommandLine|contains|all:
          - 'shimgvw.dll'
          - 'ImageView_Fullscreen'
          - 'http'
    - CommandLine|contains|all:
          - 'comsvcs.dll'
          - 'MiniDump'

Stage 2: `not filter_main_*`

filter_main_screensaver:
    CommandLine|contains: 'shell32.dll,Control_RunDLL desk.cpl,screensaver,@screensaver'
filter_main_parent_cpl:
    ParentImage: 'C:\Windows\System32\control.exe'
    ParentCommandLine|contains: '.cpl'
    CommandLine|contains|all:
        - 'Shell32.dll'
        - 'Control_RunDLL'
        - '.cpl'
filter_main_startmenu:
    ParentImage: 'C:\Windows\System32\control.exe'
    CommandLine|startswith: '"C:\Windows\system32\rundll32.exe" Shell32.dll,Control_RunDLL "C:\Windows\System32\'
    CommandLine|endswith: '.cpl",'

Exclusions

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

Field	Kind	Excluded values
`CommandLine`	ends_with	`.cpl",`
`CommandLine`	starts_with	`"C:\Windows\system32\rundll32.exe" Shell32.dll,Control_RunDLL "C:\Windows\System32\`
`ParentImage`	eq	`C:\Windows\System32\control.exe`
`CommandLine`	match	`.cpl`
`CommandLine`	match	`Control_RunDLL`
`CommandLine`	match	`Shell32.dll`
`ParentCommandLine`	match	`.cpl`
`ParentImage`	eq	`C:\Windows\System32\control.exe`
`CommandLine`	match	`shell32.dll,Control_RunDLL desk.cpl,screensaver,@screensaver`

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	`.RegisterXLL` `Control_RunDLL` corpus 5 (sigma 3, splunk 2) `FileProtocolHandler` `GenerateTypeLib` `ImageView_Fullscreen` `InstallHinfSection` `LaunchApplication` corpus 2 (sigma 2) `LaunchINFSection` `MiniDump` corpus 5 (sigma 4, chronicle 1) `OpenURL` `OpenURLA` `PrintHTML` `RegisterOCX` `RouteTheCall` `SetupInfObjectInstallAction` `ShOpenVerbApplication` `ShOpenVerbShortcut` `ShellExec_RunDLL` corpus 3 (sigma 3) `advpack.dll` `comsvcs.dll` corpus 3 (sigma 2, splunk 1) `dfshim.dll` `http` corpus 39 (sigma 34, elastic 2, chronicle 2, splunk 1) `ieadvpack.dll` `ieframe.dll` `javascript:` `mshtml.dll` `pcwutl.dll` `scrobj.dll` `setupapi.dll` `shdocvw.dll` `shell32.dll` corpus 3 (sigma 3) `shimgvw.dll` `syssetup.dll` `url.dll` `zipfldr.dll`

`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)

Potentially Suspicious Rundll32 Activity

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection`

Stage 2: `not filter_main_*`

Exclusions

Indicators

Keyboard shortcuts

Search operators

Potentially Suspicious Rundll32 Activity

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection

Stage 2: not filter_main_*

Exclusions

Indicators

Stage 0: `condition`

Stage 1: `selection`

Stage 2: `not filter_main_*`