Modification of Accessibility Features

Severity: medium
Time window: 1h
Group by: CommandLine, Computer, CurrentDirectory, Description, EventID, Hashes, Image, OriginalFileName, ParentCommandLine, ParentImage, ParentProcessGuid, ParentUser, ProcessGuid, ProcessId, User
Author: Vasileios Paschalidis
Source: github.com/Azure/Azure-Sentinel

Adversaries may establish persistence and/or elevate privileges by executing malicious content triggered by accessibility features. Windows contains accessibility features that may be launched with a key combination before a user has logged in (ex: when the user is on the Windows logon screen). An adversary can modify the way these programs are launched to get a command prompt or backdoor without logging in to the system. Two common accessibility programs are C:\Windows\System32\sethc.exe, launched when the shift key is pressed five times and C:\Windows\System32\utilman.exe, launched when the Windows + U key combination is pressed. The sethc.exe program is often referred to as "sticky keys", and has been used by adversaries for unauthenticated access through a remote desktop login screen. [1] Ref: https://attack.mitre.org/techniques/T1546/008/

MITRE ATT&CK coverage

Tactic	Techniques
Persistence	`T1546.008` Event Triggered Execution: Accessibility Features

Event coverage

Provider	Event	Title
Sysmon	Event ID 1	Process creation

Rule body kusto

id: d714ef62-1a56-4779-804f-91c4158e528d
name: Modification of Accessibility Features
description: |
  'Adversaries may establish persistence and/or elevate privileges by executing malicious content triggered by accessibility features. Windows contains accessibility features that may be launched with a key combination before a user has logged in (ex: when the user is on the Windows logon screen). An adversary can modify the way these programs are launched to get a command prompt or backdoor without logging in to the system.
  Two common accessibility programs are C:\Windows\System32\sethc.exe, launched when the shift key is pressed five times and C:\Windows\System32\utilman.exe, launched when the Windows + U key combination is pressed. The sethc.exe program is often referred to as "sticky keys", and has been used by adversaries for unauthenticated access through a remote desktop login screen. [1]
  Ref: https://attack.mitre.org/techniques/T1546/008/'
severity: Medium
requiredDataConnectors:
  - connectorId: SecurityEvents
    dataTypes:
      - SecurityEvent
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
  - Persistence
relevantTechniques:
  - T1546.008
query: |
  let ImagesList = dynamic (["sethc.exe","utilman.exe","osk.exe","Magnify.exe","Narrator.exe","DisplaySwitch.exe","AtBroker.exe"]); 
  let OriginalFileNameList = dynamic (["sethc.exe","utilman.exe","osk.exe","Magnify.exe","Narrator.exe","DisplaySwitch.exe","AtBroker.exe","SR.exe","utilman2.exe","ScreenMagnifier.exe"]); 
  Event
  | where EventLog == "Microsoft-Windows-Sysmon/Operational" and EventID==1
  | parse EventData with * 'ProcessId">' ProcessId "<" * 'Image">' Image "<" * 'OriginalFileName">' OriginalFileName "<" *
  | where Image has_any (ImagesList) and not (OriginalFileName has_any (OriginalFileNameList))
  | parse EventData with * 'ProcessGuid">' ProcessGuid "<" * 'Description">' Description "<" * 'CommandLine">' CommandLine "<" * 'CurrentDirectory">' CurrentDirectory "<" * 'User">' User "<" * 'LogonGuid">' LogonGuid "<" * 'Hashes">' Hashes "<" * 'ParentProcessGuid">' ParentProcessGuid "<" * 'ParentImage">' ParentImage "<" * 'ParentCommandLine">' ParentCommandLine "<" * 'ParentUser">' ParentUser "<" *
  | summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by EventID, Computer, User, ParentImage, ParentProcessGuid, ParentCommandLine, ParentUser, Image, ProcessId, ProcessGuid, CommandLine, Description, OriginalFileName, CurrentDirectory, Hashes
  | extend HostName = tostring(split(Computer, ".")[0]), DomainIndex = toint(indexof(Computer, '.'))
  | extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)
  | extend AccountName = tostring(split(User, "\\")[1]), AccountNTDomain = tostring(split(User, "\\")[0])
  | extend ImageFileName = tostring(split(Image, "\\")[-1])
  | extend ImageDirectory = replace_string(Image, ImageFileName, "")
  | project-away DomainIndex
entityMappings:
  - entityType: Process
    fieldMappings:
      - identifier: CommandLine
        columnName: CommandLine
      - identifier: ProcessId
        columnName: ProcessId
  - entityType: Host
    fieldMappings:
      - identifier: FullName
        columnName: Computer
      - identifier: HostName
        columnName: HostName
      - identifier: DnsDomain
        columnName: HostNameDomain
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: User
      - identifier: Name
        columnName: AccountName
      - identifier: NTDomain
        columnName: AccountNTDomain
  - entityType: File
    fieldMappings:
      - identifier: Name
        columnName: ImageFileName
      - identifier: Directory
        columnName: ImageDirectory
version: 1.0.4
kind: Scheduled
metadata:
    source:
        kind: Community
    author:
        name: Vasileios Paschalidis
    support:
        tier: Community
    categories:
        domains: [ "Security - Others" ]

Stages and Predicates

Parameters

let ImagesList = dynamic (["sethc.exe","utilman.exe","osk.exe","Magnify.exe","Narrator.exe","DisplaySwitch.exe","AtBroker.exe"]);

Let binding: `OriginalFileNameList`

let OriginalFileNameList = dynamic (["sethc.exe","utilman.exe","osk.exe","Magnify.exe","Narrator.exe","DisplaySwitch.exe","AtBroker.exe","SR.exe","utilman2.exe","ScreenMagnifier.exe"]);

Stage 1: `source`

Event

Stage 2: `where`

| where EventLog == "Microsoft-Windows-Sysmon/Operational" and EventID==1

Stage 3: `parse`

| parse EventData with * 'ProcessId">' ProcessId "<" * 'Image">' Image "<" * 'OriginalFileName">' OriginalFileName "<" *

Stage 4: `where`

| where Image has_any (ImagesList) and not (OriginalFileName has_any (OriginalFileNameList))

References OriginalFileNameList (defined above).

Stage 5: `parse`

| parse EventData with * 'ProcessGuid">' ProcessGuid "<" * 'Description">' Description "<" * 'CommandLine">' CommandLine "<" * 'CurrentDirectory">' CurrentDirectory "<" * 'User">' User "<" * 'LogonGuid">' LogonGuid "<" * 'Hashes">' Hashes "<" * 'ParentProcessGuid">' ParentProcessGuid "<" * 'ParentImage">' ParentImage "<" * 'ParentCommandLine">' ParentCommandLine "<" * 'ParentUser">' ParentUser "<" *

Stage 6: `summarize`

| summarize StartTime = min(TimeGenerated), EndTime = max(TimeGenerated) by EventID, Computer, User, ParentImage, ParentProcessGuid, ParentCommandLine, ParentUser, Image, ProcessId, ProcessGuid, CommandLine, Description, OriginalFileName, CurrentDirectory, Hashes

Stage 7: `extend` (5 consecutive steps)

| extend HostName = tostring(split(Computer, ".")[0]), DomainIndex = toint(indexof(Computer, '.'))
| extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)
| extend AccountName = tostring(split(User, "\\")[1]), AccountNTDomain = tostring(split(User, "\\")[0])
| extend ImageFileName = tostring(split(Image, "\\")[-1])
| extend ImageDirectory = replace_string(Image, ImageFileName, "")

Stage 8: `project-away`

| project-away DomainIndex

Exclusions

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

Field	Kind	Excluded values
`OriginalFileName`	match	`sethc.exe`, `utilman.exe`, `osk.exe`, `Magnify.exe`, `Narrator.exe`, `DisplaySwitch.exe`, `AtBroker.exe`, `SR.exe`, `utilman2.exe`, `ScreenMagnifier.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
`EventID`	eq	`1` transforms: `cased` corpus 237 (splunk 224, kusto 13)
`EventLog`	eq	`Microsoft-Windows-Sysmon/Operational` transforms: `cased` corpus 10 (kusto 10)
`Image`	match	`AtBroker.exe` `DisplaySwitch.exe` `Magnify.exe` `Narrator.exe` `osk.exe` `sethc.exe` `utilman.exe`

Output fields

Fields the rule emits when it matches. Chronicle authors list these in the outcome block; they appear on the detection and $risk_score drives alerting. Sentinel / Defender XDR rules build them up through project / summarize / extend stages. Sentinel maps these into alert fields via entityMappings and customDetails; Defender XDR custom detections surface them as alert fields directly.

Field	Source
`CommandLine`	`summarize`
`Computer`	`summarize`
`CurrentDirectory`	`summarize`
`Description`	`summarize`
`EndTime`	`summarize`
`EventID`	`summarize`
`Hashes`	`summarize`
`Image`	`summarize`
`OriginalFileName`	`summarize`
`ParentCommandLine`	`summarize`
`ParentImage`	`summarize`
`ParentProcessGuid`	`summarize`
`ParentUser`	`summarize`
`ProcessGuid`	`summarize`
`ProcessId`	`summarize`
`StartTime`	`summarize`
`User`	`summarize`
`HostName`	`extend`
`HostNameDomain`	`extend`
`AccountNTDomain`	`extend`
`AccountName`	`extend`
`ImageFileName`	`extend`
`ImageDirectory`	`extend`

`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)

Modification of Accessibility Features

MITRE ATT&CK coverage

Event coverage

Rule body kusto

Stages and Predicates

Parameters

Let binding: `OriginalFileNameList`

Stage 1: `source`

Stage 2: `where`

Stage 3: `parse`

Stage 4: `where`

Stage 5: `parse`

Stage 6: `summarize`

Stage 7: `extend` (5 consecutive steps)

Stage 8: `project-away`

Exclusions

Indicators

Output fields

Keyboard shortcuts

Search operators

Modification of Accessibility Features

MITRE ATT&CK coverage

Event coverage

Rule body kusto

Stages and Predicates

Parameters

Let binding: OriginalFileNameList

Stage 1: source

Stage 2: where

Stage 3: parse

Stage 4: where

Stage 5: parse

Stage 6: summarize

Stage 7: extend (5 consecutive steps)

Stage 8: project-away

Exclusions

Indicators

Output fields

Let binding: `OriginalFileNameList`

Stage 1: `source`

Stage 2: `where`

Stage 3: `parse`

Stage 4: `where`

Stage 5: `parse`

Stage 6: `summarize`

Stage 7: `extend` (5 consecutive steps)

Stage 8: `project-away`