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Detection rules › Sigma

Change User Account Associated with the FAX Service

Status
test
Severity
high
Log source
category registry_set, product windows
Author
frack113
Source
github.com/SigmaHQ/sigma

Detect change of the user account associated with the FAX service to avoid the escalation problem.

MITRE ATT&CK coverage

TacticTechniques
Persistence
Defense Impairment

Telemetry coverage

ProviderRecord / event type
SysmonEvent ID 13: RegistryEvent (Value Set)

Rule body

title: Change User Account Associated with the FAX Service
id: e3fdf743-f05b-4051-990a-b66919be1743
status: test
description: Detect change of the user account associated with the FAX service to avoid the escalation problem.
references:
    - https://twitter.com/dottor_morte/status/1544652325570191361
    - https://raw.githubusercontent.com/RiccardoAncarani/talks/master/F-Secure/unorthodox-lateral-movement.pdf
author: frack113
date: 2022-07-17
modified: 2022-12-30
tags:
    - attack.persistence
    - attack.defense-impairment
    - attack.t1112
logsource:
    product: windows
    category: registry_set
detection:
    selection:
        TargetObject: HKLM\System\CurrentControlSet\Services\Fax\ObjectName
    filter:
        Details|contains: NetworkService
    condition: selection and not filter
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: condition

selection and not filter

Stage 1: selection

selection:
    TargetObject: HKLM\System\CurrentControlSet\Services\Fax\ObjectName

Stage 2: not filter

filter:
    Details|contains: NetworkService

Exclusions

The rule actively suppresses these predicates.

FieldKindExcluded valuesSearch
DetailsmatchNetworkServiceexcludes:Details field:"Details" value:"NetworkService"

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
TargetObjecteq
  • HKLM\System\CurrentControlSet\Services\Fax\ObjectName
field:"TargetObject" kind:eq value:"HKLM\System\CurrentControlSet\Services\Fax\ObjectName"