Potential Modification of Accessibility Binaries

Last updated 5 months ago on 2025-03-20
Created 6 years ago on 2020-02-18

About

Windows contains accessibility features that may be launched with a key combination before a user has logged in. An adversary can modify the way these programs are launched to get a command prompt or backdoor without logging in to the system.
Tags
Domain: EndpointOS: WindowsUse Case: Threat DetectionTactic: PersistenceData Source: Elastic EndgameData Source: Elastic DefendData Source: SysmonData Source: Microsoft Defender for EndpointLanguage: eql
Severity
high
Risk Score
73
MITRE ATT&CK™

Persistence (TA0003)(opens in a new tab or window)

Privilege Escalation (TA0004)(opens in a new tab or window)

License
Elastic License v2(opens in a new tab or window)

Definition

Rule Type
Event Correlation Rule
Integration Pack
Prebuilt Security Detection Rules
Index Patterns
winlogbeat-*logs-endpoint.events.process-*logs-windows.sysmon_operational-*endgame-*logs-m365_defender.event-*
Related Integrations

endpoint(opens in a new tab or window)

windows(opens in a new tab or window)

m365_defender(opens in a new tab or window)

Query
process where host.os.type == "windows" and event.type == "start" and
 process.parent.name : ("Utilman.exe", "winlogon.exe") and user.name == "SYSTEM" and
 process.pe.original_file_name : "?*" and
 process.args :
    (
    "C:\\Windows\\System32\\osk.exe",
    "C:\\Windows\\System32\\Magnify.exe",
    "C:\\Windows\\System32\\Narrator.exe",
    "C:\\Windows\\System32\\Sethc.exe",
    "utilman.exe",
    "ATBroker.exe",
    "DisplaySwitch.exe",
    "sethc.exe"
    )
 and not process.pe.original_file_name in
    (
    "osk.exe",
    "sethc.exe",
    "utilman2.exe",
    "DisplaySwitch.exe",
    "ATBroker.exe",
    "ScreenMagnifier.exe",
    "SR.exe",
    "Narrator.exe",
    "magnify.exe",
    "MAGNIFY.EXE"
    )

/* uncomment once in winlogbeat to avoid bypass with rogue process with matching pe original file name */
/* and process.code_signature.subject_name == "Microsoft Windows" and process.code_signature.status == "trusted" */

Install detection rules in Elastic Security

Detect Potential Modification of Accessibility Binaries in the Elastic Security detection engine by installing this rule into your Elastic Stack.

To setup this rule, check out the installation guide for Prebuilt Security Detection Rules(opens in a new tab or window).