Suspicious File Execution From Internet Hosted WebDav Share

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

Detects the execution of the "net use" command to mount a WebDAV server and then immediately execute some content in it. As seen being used in malicious LNK files

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1059.001` Command and Scripting Interpreter: PowerShell

Telemetry coverage

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

Rule body

title: Suspicious File Execution From Internet Hosted WebDav Share
id: f0507c0f-a3a2-40f5-acc6-7f543c334993
status: test
description: Detects the execution of the "net use" command to mount a WebDAV server and then immediately execute some content in it. As seen being used in malicious LNK files
references:
    - https://twitter.com/ShadowChasing1/status/1552595370961944576
    - https://www.virustotal.com/gui/file/a63376ee1dba76361df73338928e528ca5b20171ea74c24581605366dcaa0104/behavior
author: pH-T (Nextron Systems)
date: 2022-09-01
modified: 2023-02-21
tags:
    - attack.execution
    - attack.t1059.001
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|contains: '\cmd.exe'
        - OriginalFileName: 'Cmd.EXE'
    selection_base:
        CommandLine|contains|all:
            - ' net use http'
            - '& start /b '
            - '\DavWWWRoot\'
    selection_ext:
        CommandLine|contains:
            - '.exe '
            - '.dll '
            - '.bat '
            - '.vbs '
            - '.ps1 '
    condition: all of selection_*
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: `condition`

all of selection_*

Stage 1: `selection_img`

selection_img:
    - Image|contains: '\cmd.exe'
    - OriginalFileName: 'Cmd.EXE'

Stage 2: `selection_base`

selection_base:
    CommandLine|contains|all:
        - ' net use http'
        - '& start /b '
        - '\DavWWWRoot\'

Stage 3: `selection_ext`

selection_ext:
    CommandLine|contains:
        - '.exe '
        - '.dll '
        - '.bat '
        - '.vbs '
        - '.ps1 '

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`net use http` `& start /b` `.bat` `.dll` `.exe` corpus 2 (sigma 2) `.ps1` `.vbs` corpus 2 (sigma 2) `\DavWWWRoot\` corpus 3 (sigma 2, elastic 1)	`field:"CommandLine" kind:match`
`Image`	match	`\cmd.exe`	`field:"Image" kind:match value:"\cmd.exe"`
`OriginalFileName`	eq	`Cmd.EXE` corpus 81 (sigma 43, elastic 21, splunk 17)	`field:"OriginalFileName" kind:eq value:"Cmd.EXE"`