Windows: Files created by Microsoft Sync Center (mobsync.exe) with .dll/.exe extensions

Flags .dll and .exe files created by mobsync.exe on Windows.

FreeReviewedSigma · Medium · v2

Product: windows
Category: file_event
Author: elhoim (SigmaHQ), DRL 1.1
Published: 2022-04-28
Updated: 2026-07-31

ATT&CK techniques

Priv Esc → Defense Evasion

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
- T1055Process Injection
Defense Evasion
- T1055Process Injection
- T1218System Binary Proxy Execution
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags file creation events where the creating process is Microsoft Sync Center (mobsync.exe) and the created file ends with .dll or .exe. Attackers can abuse legitimate sync functionality to drop or stage executable payloads while blending in with normal system activity. It relies on Windows file event telemetry that records the process image path and the target filename for the creation event.

Reporting behind it

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Windows: Files created by Microsoft Sync Center (mobsync.exe) with .dll/.exe extensions

Pivot detection · T1055 · 9 related

Changelog

v2
Candidate ingested via manual entry.2026-07-31
v1
No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

windows-files-created-by-microsoft-sync-center-mobsync-exe-409f8a98

title: "Windows: Files created by Microsoft Sync Center (mobsync.exe) with .dll/.exe extensions"
id: d7dc7168-d016-4dba-929d-0ead09792cca
status: test
description: This rule flags file creation events where the creating process is Microsoft Sync Center (mobsync.exe) and the created file ends with .dll or .exe. Attackers can abuse legitimate sync functionality to drop or stage executable payloads while blending in with normal system activity. It relies on Windows file event telemetry that records the process image path and the target filename for the creation event.
references:
  - https://redcanary.com/blog/intelligence-insights-november-2021/
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/file/file_event/file_event_win_susp_creation_by_mobsync.yml
author: elhoim, Huntrule Team
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
license: DRL-1.1
related:
  - id: 409f8a98-4496-4aaa-818a-c931c0a8b832
    type: derived

Convert

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