ProxyLogon Reset Virtual Directories Based On IIS Log

When exploiting this vulnerability with CVE-2021-26858, an SSRF attack is used to manipulate virtual directories

Detection logic

selection

cs-method: POST
sc-status: 200
cs-uri-stem: /ecp/DDI/DDIService.svc/SetObject
cs-uri-query|contains|all:
  - schema=Reset
  - VirtualDirectory
cs-username|endswith: $

keywords

"|all":
  - POST
  - 200
  - /ecp/DDI/DDIService.svc/SetObject
  - schema=Reset
  - VirtualDirectory
  - $

Condition

selection or keywords

Raw YAML

title: ProxyLogon Reset Virtual Directories Based On IIS Log
id: effee1f6-a932-4297-a81f-acb44064fa3a
status: test
description: When exploiting this vulnerability with CVE-2021-26858, an SSRF attack is used to manipulate virtual directories
references:
    - https://bi-zone.medium.com/hunting-down-ms-exchange-attacks-part-1-proxylogon-cve-2021-26855-26858-27065-26857-6e885c5f197c
author: frack113
date: 2021-08-10
modified: 2023-05-08
tags:
    - cve.2021-26858
    - detection.emerging-threats
    - attack.initial-access
    - attack.t1190
logsource:
    category: webserver
    definition: 'Requirements: The POST request body data must be collected in order to make use of this detection'
detection:
    selection:
        cs-method: 'POST'
        sc-status: 200
        cs-uri-stem: '/ecp/DDI/DDIService.svc/SetObject'
        cs-uri-query|contains|all:
            - 'schema=Reset'
            - 'VirtualDirectory'
        cs-username|endswith: '$'
    keywords:
        '|all':
            - 'POST'
            - 200
            - '/ecp/DDI/DDIService.svc/SetObject'
            - 'schema=Reset'
            - 'VirtualDirectory'
            - '$'
    condition: selection or keywords
falsepositives:
    - Unlikely
level: critical