Renamed AutoIt Execution

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

Detects the execution of a renamed AutoIt2.exe or AutoIt3.exe. AutoIt is a scripting language and automation tool for Windows systems. While primarily used for legitimate automation tasks, it can be misused in cyber attacks. Attackers can leverage AutoIt to create and distribute malware, including keyloggers, spyware, and botnets. A renamed AutoIt executable is particularly suspicious.

MITRE ATT&CK coverage

Tactic	Techniques
Stealth	`T1027` Obfuscated Files or Information

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 1: Process creation

Rule body

title: Renamed AutoIt Execution
id: f4264e47-f522-4c38-a420-04525d5b880f
status: test
description: |
    Detects the execution of a renamed AutoIt2.exe or AutoIt3.exe.
    AutoIt is a scripting language and automation tool for Windows systems. While primarily used for legitimate automation tasks, it can be misused in cyber attacks.
    Attackers can leverage AutoIt to create and distribute malware, including keyloggers, spyware, and botnets. A renamed AutoIt executable is particularly suspicious.
references:
    - https://twitter.com/malmoeb/status/1665463817130725378?s=12&t=C0_T_re0wRP_NfKa27Xw9w
    - https://www.autoitscript.com/site/
author: Florian Roth (Nextron Systems)
date: 2023-06-04
modified: 2024-11-23
tags:
    - attack.stealth
    - attack.t1027
logsource:
    category: process_creation
    product: windows
detection:
    selection_1:
        CommandLine|contains:
            - ' /AutoIt3ExecuteScript'
            - ' /ErrorStdOut'
    selection_2:
        Hashes|contains:
            - 'IMPHASH=FDC554B3A8683918D731685855683DDF'  # AutoIt v2 - doesn't cover all binaries
            - 'IMPHASH=CD30A61B60B3D60CECDB034C8C83C290'  # AutoIt v2 - doesn't cover all binaries
            - 'IMPHASH=F8A00C72F2D667D2EDBB234D0C0AE000'  # AutoIt v3 - doesn't cover all binaries
    selection_3:
        OriginalFileName:
            - 'AutoIt3.exe'
            - 'AutoIt2.exe'
            - 'AutoIt.exe'
    filter_main_legit_name:
        Image|endswith:
            - '\AutoIt.exe'
            - '\AutoIt2.exe'
            - '\AutoIt3_x64.exe'
            - '\AutoIt3.exe'
    condition: 1 of selection_* and not 1 of filter_main_*
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: `condition`

1 of selection_* and not 1 of filter_main_*

Stage 1: `selection_1`

selection_1:
    CommandLine|contains:
        - ' /AutoIt3ExecuteScript'
        - ' /ErrorStdOut'

Stage 2: `selection_2`

selection_2:
    Hashes|contains:
        - 'IMPHASH=FDC554B3A8683918D731685855683DDF'
        - 'IMPHASH=CD30A61B60B3D60CECDB034C8C83C290'
        - 'IMPHASH=F8A00C72F2D667D2EDBB234D0C0AE000'

Stage 3: `selection_3`

selection_3:
    OriginalFileName:
        - 'AutoIt3.exe'
        - 'AutoIt2.exe'
        - 'AutoIt.exe'

Stage 4: `not filter_main_legit_name`

filter_main_legit_name:
    Image|endswith:
        - '\AutoIt.exe'
        - '\AutoIt2.exe'
        - '\AutoIt3_x64.exe'
        - '\AutoIt3.exe'

Exclusions

The rule actively suppresses these predicates.

Field	Kind	Excluded values	Search
`Image`	ends_with	`\AutoIt.exe`	`excludes:Image` `field:"Image" value:"\AutoIt.exe"`
`Image`	ends_with	`\AutoIt2.exe`	`excludes:Image` `field:"Image" value:"\AutoIt2.exe"`
`Image`	ends_with	`\AutoIt3.exe`	`excludes:Image` `field:"Image" value:"\AutoIt3.exe"`
`Image`	ends_with	`\AutoIt3_x64.exe`	`excludes:Image` `field:"Image" value:"\AutoIt3_x64.exe"`

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`/AutoIt3ExecuteScript` `/ErrorStdOut`	`field:"CommandLine" kind:match`
`Hashes`	match	`IMPHASH=CD30A61B60B3D60CECDB034C8C83C290` `IMPHASH=F8A00C72F2D667D2EDBB234D0C0AE000` `IMPHASH=FDC554B3A8683918D731685855683DDF`	`field:"Hashes" kind:match`
`OriginalFileName`	eq	`AutoIt.exe` `AutoIt2.exe` `AutoIt3.exe` corpus 2 (sigma 2)	`field:"OriginalFileName" kind:eq`