HackTool - Jlaive In-Memory Assembly Execution

Status: test
Severity: medium
Log source: category process_creation, product windows
Author: Jose Luis Sanchez Martinez (@Joseliyo_Jstnk)
Source: github.com/SigmaHQ/sigma

Detects the use of Jlaive to execute assemblies in a copied PowerShell

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1059.003` Command and Scripting Interpreter: Windows Command Shell

Telemetry coverage

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

Rule body

title: HackTool - Jlaive In-Memory Assembly Execution
id: 0a99eb3e-1617-41bd-b095-13dc767f3def
status: test
description: Detects the use of Jlaive to execute assemblies in a copied PowerShell
references:
    - https://jstnk9.github.io/jstnk9/research/Jlaive-Antivirus-Evasion-Tool
    - https://web.archive.org/web/20220514073704/https://github.com/ch2sh/Jlaive
author: Jose Luis Sanchez Martinez (@Joseliyo_Jstnk)
date: 2022-05-24
modified: 2023-02-22
tags:
    - attack.execution
    - attack.t1059.003
logsource:
    product: windows
    category: process_creation
detection:
    parent_selection:
        ParentImage|endswith: '\cmd.exe'
        ParentCommandLine|endswith: '.bat'
    selection1:
        Image|endswith: '\xcopy.exe'
        CommandLine|contains|all:
            - 'powershell.exe'
            - '.bat.exe'
    selection2:
        Image|endswith: '\xcopy.exe'
        CommandLine|contains|all:
            - 'pwsh.exe'
            - '.bat.exe'
    selection3:
        Image|endswith: '\attrib.exe'
        CommandLine|contains|all:
            - '+s'
            - '+h'
            - '.bat.exe'
    condition: parent_selection and (1 of selection*)
falsepositives:
    - Unknown
level: medium

Stages and Predicates

Stage 0: `condition`

parent_selection and (1 of selection*)

Stage 1: `parent_selection`

parent_selection:
    ParentImage|endswith: '\cmd.exe'
    ParentCommandLine|endswith: '.bat'

Stage 2: `selection1`

selection1:
    Image|endswith: '\xcopy.exe'
    CommandLine|contains|all:
        - 'powershell.exe'
        - '.bat.exe'

Stage 3: `selection2`

selection2:
    Image|endswith: '\xcopy.exe'
    CommandLine|contains|all:
        - 'pwsh.exe'
        - '.bat.exe'

Stage 4: `selection3`

selection3:
    Image|endswith: '\attrib.exe'
    CommandLine|contains|all:
        - '+s'
        - '+h'
        - '.bat.exe'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`+h` corpus 2 (sigma 1, splunk 1) `+s` `.bat.exe` `powershell.exe` corpus 2 (sigma 2) `pwsh.exe` corpus 2 (sigma 2)	`field:"CommandLine" kind:match`
`Image`	ends_with	`\attrib.exe` corpus 5 (sigma 5) `\xcopy.exe` corpus 5 (sigma 5)	`field:"Image" kind:ends_with`
`ParentCommandLine`	ends_with	`.bat`	`field:"ParentCommandLine" kind:ends_with value:".bat"`
`ParentImage`	ends_with	`\cmd.exe` corpus 20 (sigma 20)	`field:"ParentImage" kind:ends_with value:"\cmd.exe"`

HackTool - Jlaive In-Memory Assembly Execution

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Stage 0: condition

Stage 1: parent_selection

Stage 2: selection1

Stage 3: selection2

Stage 4: selection3

Indicators

Stage 0: `condition`

Stage 1: `parent_selection`

Stage 2: `selection1`

Stage 3: `selection2`

Stage 4: `selection3`