IMPORTANT: No additional bug fixes or documentation updates will be released for this version. For the latest information, see the current release documentation.
« Microsoft Exchange Server UM Writing Suspicious Files Microsoft Exchange Worker Spawning Suspicious Processes »
Elastic Docs ›Elastic Security Solution [7.16] ›Downloadable rule update v0.16.2

Microsoft Exchange Server UM Spawning Suspicious Processes

edit

Microsoft Exchange Server UM Spawning Suspicious Processes

edit

Identifies suspicious processes being spawned by the Microsoft Exchange Server Unified Messaging (UM) service. This activity has been observed exploiting CVE-2021-26857.

Rule type: eql

Rule indices:

  • logs-endpoint.events.*
  • winlogbeat-*
  • logs-windows.*

Severity: medium

Risk score: 47

Runs every: 5m

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

  • Elastic
  • Host
  • Windows
  • Threat Detection
  • Initial Access

Version: 2

Rule authors:

  • Elastic
  • Austin Songer

Rule license: Elastic License v2

Investigation guide

edit
## Config

If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2, events will not define `event.ingested` and default fallback for EQL rules was not added until 8.2, so you will need to add a custom pipeline to populate `event.ingested` to @timestamp for this rule to work.

Rule query

edit
process where event.type == "start" and
  process.parent.name : ("UMService.exe", "UMWorkerProcess.exe") and
    not process.name : ("werfault.exe", "wermgr.exe")

Framework: MITRE ATT&CKTM

« Microsoft Exchange Server UM Writing Suspicious Files Microsoft Exchange Worker Spawning Suspicious Processes »