SMBexec.py Execution

SIGMA detection rule by RedCanary, Sigma formatting by Micah Babinski · GPL-3.0

Similar to the wmiexec.py detector logic, this detection analytic is looking for services.exe spawning cmd.exe with a command line that has the following strings: '/Q', '/c', 'echo',' > ', ' 2>&1'. These strings are unique to the execution of smbexec.py, which allows a semi-interactive shell used through SMB. This script functions similar to psexec.py, but does not write a service binary to disk on the target machine. Part of the RedCanary 2024 Threat Detection Report.

title: SMBexec.py Execution
id: c250b516-78d8-4664-8b86-8f3c9c0b53c8
status: experimental
description: |
    Similar to the wmiexec.py detector logic, this detection analytic is looking for services.exe 
    spawning cmd.exe with a command line that has the following strings: '/Q', '/c', 'echo',' > ', 
    ' 2>&1'. These strings are unique to the execution of smbexec.py, which allows a semi-interactive 
    shell used through SMB. This script functions similar to psexec.py, but does not write a service 
    binary to disk on the target machine. Part of the RedCanary 2024 Threat Detection Report.
references:
    - https://redcanary.com/threat-detection-report/threats/impacket/
author: RedCanary, Sigma formatting by Micah Babinski
date: 2024/03/21
tags:
    - attack.s0357
    - attack.execution
    - attack.t1569
    - attack.t1569.002
    - attack.lateral_movement
    - attack.t1021
    - attack.t1021.003
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith: '\services.exe'
        Image|endswith: '\cmd.exe'
        CommandLine|contains:
            - '/Q'
            - '/c'
            - 'echo'
            - '^> '
            - ' 2^>^&1 > '
    condition: selection
falsepositives:
    - Unknown
level: low

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

44c401d6-f63b-4ee3-a414-4bdbf8647513

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Executable code, not a declarative rule

This submission is arbitrary [[ currentRule.format ? currentRule.format.toUpperCase() : '' ]] code, not a declarative detection rule — review it as you would any script before running it, and note that it cannot be safely aggregated or auto-executed alongside YARA/Sigma/Suricata/CRS rules.

Rejected pattern present

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Format & documentation suggestions

Not a security issue — this rule is valid and was accepted as-is. These are optional fields/conventions its own format recommends, mainly affecting its quality score and how well it documents itself for other reviewers.

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[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

[[ currentRule.title ]]

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