Share And Session Enumeration Using Net.EXE

Status: stable
Severity: low
Log source: category process_creation, product windows
Author: Endgame, JHasenbusch (ported for oscd.community)
Source: github.com/SigmaHQ/sigma

Detects attempts to enumerate file shares, printer shares and sessions using "net.exe" with the "view" flag.

Known false positives

Legitimate use of net.exe utility by legitimate user

MITRE ATT&CK coverage

Tactic	Techniques
Discovery	`T1018` Remote System Discovery

Telemetry coverage

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

Rule body

title: Share And Session Enumeration Using Net.EXE
id: 62510e69-616b-4078-b371-847da438cc03
status: stable
description: Detects attempts to enumerate file shares, printer shares and sessions using "net.exe" with the "view" flag.
references:
    - https://eqllib.readthedocs.io/en/latest/analytics/b8a94d2f-dc75-4630-9d73-1edc6bd26fff.html
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1018/T1018.md
author: Endgame, JHasenbusch (ported for oscd.community)
date: 2018-10-30
modified: 2023-02-21
tags:
    - attack.discovery
    - attack.t1018
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith:
              - '\net.exe'
              - '\net1.exe'
        - OriginalFileName:
              - 'net.exe'
              - 'net1.exe'
    selection_cli:
        CommandLine|contains: 'view'
    filter:
        CommandLine|contains: '\\\\'
    condition: all of selection_* and not filter
falsepositives:
    - Legitimate use of net.exe utility by legitimate user
level: low

Stages and Predicates

Stage 0: `condition`

all of selection_* and not filter

Stage 1: `selection_img`

selection_img:
    - Image|endswith:
          - '\net.exe'
          - '\net1.exe'
    - OriginalFileName:
          - 'net.exe'
          - 'net1.exe'

Stage 2: `selection_cli`

selection_cli:
    CommandLine|contains: 'view'

Stage 3: `not filter`

filter:
    CommandLine|contains: '\\\\'

Exclusions

The rule actively suppresses these predicates.

Field	Kind	Excluded values	Search
`CommandLine`	match	`\\\\`	`excludes:CommandLine` `field:"CommandLine" value:"\\\\"`

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`view` corpus 2 (sigma 1, splunk 1)	`field:"CommandLine" kind:match value:"view"`
`Image`	ends_with	`\net.exe` corpus 49 (sigma 49) `\net1.exe` corpus 47 (sigma 47)	`field:"Image" kind:ends_with`
`OriginalFileName`	eq	`net.exe` corpus 31 (sigma 19, elastic 10, splunk 2) `net1.exe` corpus 44 (sigma 19, splunk 19, elastic 6)	`field:"OriginalFileName" kind:eq`