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Detection rules › Sigma

Remote Schedule Task Recon via AtScv

Status
test
Severity
high
Log source
category application, product rpc_firewall
Author
Sagie Dulce, Dekel Paz
Source
github.com/SigmaHQ/sigma

Detects remote RPC calls to read information about scheduled tasks via AtScv

MITRE ATT&CK coverage

TacticTechniques
DiscoveryNo specific technique

Telemetry coverage

ProviderRecord / event type
RPCFWEvent ID 3: An RPC server function was called.

Rule body

title: Remote Schedule Task Recon via AtScv
id: f177f2bc-5f3e-4453-b599-57eefce9a59c
status: test
description: Detects remote RPC calls to read information about scheduled tasks via AtScv
references:
    - https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-tsch/d1058a28-7e02-4948-8b8d-4a347fa64931
    - https://github.com/zeronetworks/rpcfirewall
    - https://github.com/jsecurity101/MSRPC-to-ATTACK/blob/ddd4608fe8684fcf2fcf9b48c5f0b3c28097f8a3/documents/MS-TSCH.md
    - https://zeronetworks.com/blog/stopping-lateral-movement-via-the-rpc-firewall/
author: Sagie Dulce, Dekel Paz
date: 2022-01-01
tags:
    - attack.discovery
logsource:
    product: rpc_firewall
    category: application
    definition: 'Requirements: install and apply the RPC Firewall to all processes with "audit:true action:block uuid:1ff70682-0a51-30e8-076d-740be8cee98b"'
detection:
    selection:
        EventLog: RPCFW
        EventID: 3
        InterfaceUuid: 1ff70682-0a51-30e8-076d-740be8cee98b
    filter:
        OpNum:
            - 0
            - 1
    condition: selection and not filter
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: condition

selection and not filter

Stage 1: selection

selection:
    EventLog: RPCFW
    EventID: 3
    InterfaceUuid: 1ff70682-0a51-30e8-076d-740be8cee98b

Stage 2: not filter

filter:
    OpNum:
        - 0
        - 1

Exclusions

The rule actively suppresses these predicates.

FieldKindExcluded valuesSearch
OpNumeq0excludes:OpNum field:"OpNum" value:"0"
OpNumeq1excludes:OpNum field:"OpNum" value:"1"

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
EventLogeq
  • RPCFW corpus 17 (sigma 17)
field:"EventLog" kind:eq value:"RPCFW"
InterfaceUuideq
  • 1ff70682-0a51-30e8-076d-740be8cee98b corpus 2 (sigma 2)
field:"InterfaceUuid" kind:eq value:"1ff70682-0a51-30e8-076d-740be8cee98b"