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Detection rules › Sigma

Created Files by Microsoft Sync Center

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

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

MITRE ATT&CK coverage

TacticTechniques
Privilege EscalationT1055 Process Injection
StealthT1055 Process Injection, T1218 System Binary Proxy Execution

Event coverage

ProviderEventTitle
SysmonEvent ID 11FileCreate

Rule body yaml

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

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
Imageends_with
  • \mobsync.exe corpus 2 (sigma 2)
TargetFilenameends_with
  • .dll corpus 23 (sigma 23)
  • .exe corpus 21 (sigma 20, splunk 1)