Possible DCSync Attack — Sigma Rule

Rule metadata and linked tags

Author: Sagie Dulce, Dekel Paz. Source status: test; severity: high. Source dates: 2022-01-01 / not supplied.

{
  "product": "rpc_firewall",
  "category": "application",
  "definition": "Requirements: install and apply the RPC Firewall to all processes, enable DRSR UUID (e3514235-4b06-11d1-ab04-00c04fc2dcd2) for \"dangerous\" opcodes (not 0,1 or 12) only from trusted IPs (DCs)"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 3a428d554d0ac8a49a5dcf997b9a44c428a174850ca8ffe4afc7f63adddc1a56

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Possible DCSync Attack
id: 56fda488-113e-4ce9-8076-afc2457922c3
status: test
description: Detects remote RPC calls to MS-DRSR from non DC hosts, which could indicate DCSync / DCShadow attacks.
references:
    - https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-drsr/f977faaa-673e-4f66-b9bf-48c640241d47?redirectedfrom=MSDN
    - https://github.com/jsecurity101/MSRPC-to-ATTACK/blob/ddd4608fe8684fcf2fcf9b48c5f0b3c28097f8a3/documents/MS-DRSR.md
    - https://github.com/zeronetworks/rpcfirewall
    - https://zeronetworks.com/blog/stopping-lateral-movement-via-the-rpc-firewall/
author: Sagie Dulce, Dekel Paz
date: 2022-01-01
tags:
    - attack.t1033
    - attack.discovery
logsource:
    product: rpc_firewall
    category: application
    definition: 'Requirements: install and apply the RPC Firewall to all processes, enable DRSR UUID (e3514235-4b06-11d1-ab04-00c04fc2dcd2) for "dangerous" opcodes (not 0,1 or 12) only from trusted IPs (DCs)'
detection:
    selection:
        EventLog: RPCFW
        EventID: 3
        InterfaceUuid: e3514235-4b06-11d1-ab04-00c04fc2dcd2
    filter:
        OpNum:
            - 0
            - 1
            - 12
    condition: selection and not filter
falsepositives:
    - Unknown
level: high

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-drsr/f977faaa-673e-4f66-b9bf-48c640241d47?redirectedfrom=MSDN
• https://github.com/jsecurity101/MSRPC-to-ATTACK/blob/ddd4608fe8684fcf2fcf9b48c5f0b3c28097f8a3/documents/MS-DRSR.md
• https://github.com/zeronetworks/rpcfirewall
• https://zeronetworks.com/blog/stopping-lateral-movement-via-the-rpc-firewall/