Potential DLL Injection Via AccCheckConsole

Status: test
Severity: medium
Log source: product windows, category process_creation
Author: Florian Roth (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects the execution "AccCheckConsole" a command-line tool for verifying the accessibility implementation of an application's UI. One of the tests that this checker can run are called "verification routine", which tests for things like Consistency, Navigation, etc. The tool allows a user to provide a DLL that can contain a custom "verification routine". An attacker can build such DLLs and pass it via the CLI, which would then be loaded in the context of the "AccCheckConsole" utility.

MITRE ATT&CK coverage

Tactic	Techniques
Execution	No specific technique

Event coverage

Provider	Event	Title
Sysmon	Event ID 1	Process creation

Rule body yaml

title: Potential DLL Injection Via AccCheckConsole
id: 0f6da907-5854-4be6-859a-e9958747b0aa
status: test
description: |
    Detects the execution "AccCheckConsole" a command-line tool for verifying the accessibility implementation of an application's UI.
    One of the tests that this checker can run are called "verification routine", which tests for things like Consistency, Navigation, etc.
    The tool allows a user to provide a DLL that can contain a custom "verification routine". An attacker can build such DLLs and pass it via the CLI, which would then be loaded in the context of the "AccCheckConsole" utility.
references:
    - https://gist.github.com/bohops/2444129419c8acf837aedda5f0e7f340
    - https://twitter.com/bohops/status/1477717351017680899?s=12
    - https://lolbas-project.github.io/lolbas/OtherMSBinaries/AccCheckConsole/
author: Florian Roth (Nextron Systems)
date: 2022-01-06
modified: 2024-08-29
tags:
    - attack.execution
    - detection.threat-hunting
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\AccCheckConsole.exe'
        - OriginalFileName: 'AccCheckConsole.exe'
    selection_cli:
        CommandLine|contains:
            - ' -hwnd'
            - ' -process '
            - ' -window '
    condition: all of selection_*
falsepositives:
    - Legitimate use of the UI Accessibility Checker
level: medium

Stages and Predicates

Stage 0: `condition`

all of selection_*

Stage 1: `selection_img`

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

Stage 2: `selection_cli`

selection_cli:
    CommandLine|contains:
        - ' -hwnd'
        - ' -process '
        - ' -window '

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	`-hwnd` `-process` `-window`
`Image`	ends_with	`\AccCheckConsole.exe`
`OriginalFileName`	eq	`AccCheckConsole.exe`

`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)

Potential DLL Injection Via AccCheckConsole

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection_img`

Stage 2: `selection_cli`

Indicators

Keyboard shortcuts

Search operators

Potential DLL Injection Via AccCheckConsole

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection_img

Stage 2: selection_cli

Indicators

Stage 0: `condition`

Stage 1: `selection_img`

Stage 2: `selection_cli`