Detection rules › Sigma

Unmount Share Via Net.EXE

Status
test
Severity
low
Log source
product windows, category process_creation
Author
oscd.community, @redcanary, Zach Stanford @svch0st
Source
github.com/SigmaHQ/sigma

Detects when when a mounted share is removed. Adversaries may remove share connections that are no longer useful in order to clean up traces of their operation

MITRE ATT&CK coverage

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation

Rule body yaml

title: Unmount Share Via Net.EXE
id: cb7c4a03-2871-43c0-9bbb-18bbdb079896
status: test
description: Detects when when a mounted share is removed. Adversaries may remove share connections that are no longer useful in order to clean up traces of their operation
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1070.005/T1070.005.md
author: oscd.community, @redcanary, Zach Stanford @svch0st
date: 2020-10-08
modified: 2023-02-21
tags:
    - attack.stealth
    - attack.t1070.005
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith:
              - '\net.exe'
              - '\net1.exe'
        - OriginalFileName:
              - 'net.exe'
              - 'net1.exe'
    selection_cli:
        CommandLine|contains|all:
            - 'share'
            - '/delete'
    condition: all of selection*
falsepositives:
    - Administrators or Power users may remove their shares via cmd line
level: low

Stages and Predicates

Stage 0: condition

all of selection*

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|all:
        - 'share'
        - '/delete'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
CommandLinematch
  • /delete corpus 8 (sigma 6, splunk 2)
  • share corpus 2 (sigma 2)
Imageends_with
  • \net.exe corpus 49 (sigma 49)
  • \net1.exe corpus 47 (sigma 47)
OriginalFileNameeq
  • net.exe corpus 28 (sigma 19, elastic 7, splunk 2)
  • net1.exe corpus 44 (sigma 19, splunk 19, elastic 6)