Detection rules › Sigma
Remote Encrypting File System Abuse
Detects remote RPC calls to possibly abuse remote encryption service via MS-EFSR
Known false positives
- Legitimate usage of remote file encryption
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Lateral Movement | No specific technique |
Telemetry coverage
| Provider | Record / event type |
|---|---|
| RPCFW | Event ID 3: An RPC server function was called. |
Rule body
title: Remote Encrypting File System Abuse
id: 5f92fff9-82e2-48eb-8fc1-8b133556a551
status: test
description: Detects remote RPC calls to possibly abuse remote encryption service via MS-EFSR
references:
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-36942
- https://github.com/jsecurity101/MSRPC-to-ATTACK/blob/ddd4608fe8684fcf2fcf9b48c5f0b3c28097f8a3/documents/MS-EFSR.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.lateral-movement
logsource:
product: rpc_firewall
category: application
definition: 'Requirements: install and apply the RPC Firewall to all processes with "audit:true action:block uuid:df1941c5-fe89-4e79-bf10-463657acf44d or c681d488-d850-11d0-8c52-00c04fd90f7e'
detection:
selection:
EventLog: RPCFW
EventID: 3
InterfaceUuid:
- df1941c5-fe89-4e79-bf10-463657acf44d
- c681d488-d850-11d0-8c52-00c04fd90f7e
condition: selection
falsepositives:
- Legitimate usage of remote file encryption
level: high
Stages and Predicates
Stage 0: condition
selectionStage 1: selection
selection:
EventLog: RPCFW
EventID: 3
InterfaceUuid:
- df1941c5-fe89-4e79-bf10-463657acf44d
- c681d488-d850-11d0-8c52-00c04fd90f7e
Indicators
These rows show field, operator, and value matches.
| Field | Kind | Values | Search |
|---|---|---|---|
EventLog | eq |
| field:"EventLog" kind:eq value:"RPCFW" |
InterfaceUuid | eq |
| field:"InterfaceUuid" kind:eq |