Detection rules › Sigma

Microsoft Sync Center Suspicious Network Connections

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

Detects suspicious connections from Microsoft Sync Center to non-private IPs.

MITRE ATT&CK coverage

Telemetry coverage

ProviderRecord / event type
SysmonEvent ID 3: Network connection

Rule body

title: Microsoft Sync Center Suspicious Network Connections
id: 9f2cc74d-78af-4eb2-bb64-9cd1d292b87b
status: test
description: Detects suspicious connections from Microsoft Sync Center to non-private IPs.
references:
    - https://redcanary.com/blog/intelligence-insights-november-2021/
author: elhoim
date: 2022-04-28
modified: 2024-03-12
tags:
    - attack.privilege-escalation
    - attack.stealth
    - attack.t1055
    - attack.t1218
    - attack.execution
logsource:
    product: windows
    category: network_connection
detection:
    selection:
        Image|endswith: '\mobsync.exe'
    filter_main_local_ranges:
        DestinationIp|cidr:
            - '127.0.0.0/8'
            - '10.0.0.0/8'
            - '172.16.0.0/12'
            - '192.168.0.0/16'
            - '169.254.0.0/16'
            - '::1/128'  # IPv6 loopback
            - 'fe80::/10'  # IPv6 link-local addresses
            - 'fc00::/7'  # IPv6 private addresses
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Unknown
level: medium

Stages and Predicates

Stage 0: condition

selection and not 1 of filter_main_*

Stage 1: selection

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

Stage 2: not filter_main_local_ranges

filter_main_local_ranges:
    DestinationIp|cidr:
        - '127.0.0.0/8'
        - '10.0.0.0/8'
        - '172.16.0.0/12'
        - '192.168.0.0/16'
        - '169.254.0.0/16'
        - '::1/128'
        - 'fe80::/10'
        - 'fc00::/7'

Exclusions

The rule actively suppresses these predicates.

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"