Detection rules › Sigma

Created Files by Microsoft Sync Center

Status
test
Severity
medium
Log source
category file_event, product windows
Author
elhoim
Source
github.com/SigmaHQ/sigma

This rule detects suspicious files created by Microsoft Sync Center (mobsync)

MITRE ATT&CK coverage

Telemetry coverage

ProviderRecord / event type
SysmonEvent ID 11: FileCreate

Rule body

title: Created Files by Microsoft Sync Center
id: 409f8a98-4496-4aaa-818a-c931c0a8b832
status: test
description: This rule detects suspicious files created by Microsoft Sync Center (mobsync)
references:
    - https://redcanary.com/blog/intelligence-insights-november-2021/
author: elhoim
date: 2022-04-28
modified: 2022-06-02
tags:
    - attack.privilege-escalation
    - attack.stealth
    - attack.t1055
    - attack.t1218
    - attack.execution
logsource:
    product: windows
    category: file_event
detection:
    selection_mobsync:
        Image|endswith: '\mobsync.exe'
    filter_created_file:
        TargetFilename|endswith:
            - '.dll'
            - '.exe'
    condition: selection_mobsync and filter_created_file
falsepositives:
    - Unknown
level: medium

Stages and Predicates

Stage 0: condition

selection_mobsync and filter_created_file

Stage 1: selection_mobsync

selection_mobsync:
    Image|endswith: '\mobsync.exe'

Stage 2: filter_created_file

filter_created_file:
    TargetFilename|endswith:
        - '.dll'
        - '.exe'

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
Imageends_with
  • \mobsync.exe corpus 2 (sigma 2)
field:"Image" kind:ends_with value:"\mobsync.exe"
TargetFilenameends_with
  • .dll corpus 24 (sigma 24)
  • .exe corpus 21 (sigma 20, splunk 1)
field:"TargetFilename" kind:ends_with