Webserver Request Matching for CVE-2020-0688 Exploitation Attempt

Alerts when webserver URI queries include /ecp/default.aspx with __VIEWSTATEGENERATOR and __VIEWSTATE consistent with CVE-2020-0688 probing.

FreeReviewedSigma · High · v5

Category: webserver
Author: NVISO (SigmaHQ), DRL 1.1
Published: 2020-02-27
Updated: 2026-07-31

Analysis Detection

ATT&CK techniques

Initial Access

Recon
Resource Dev
Initial Access
- T1190Exploit Public-Facing Application
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule identifies web requests whose URI query contains the Exchange ecx/default.aspx endpoint along with ASP.NET ViewState parameters (__VIEWSTATEGENERATOR and __VIEWSTATE). Attackers may use crafted ViewState data to target known vulnerable behavior, making these specific query components a useful early signal. The detection relies on webserver telemetry that captures the full request URI query string.

Reporting behind it

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Webserver Request Matching for CVE-2020-0688 Exploitation Attempt

Pivot detection · T1190 · 9 related

Changelog

v5
Candidate ingested via manual entry.2026-07-31
v4
Candidate ingested via manual entry.2026-07-31
v3
Candidate ingested via manual entry.2026-07-31
v2
Candidate ingested via manual entry.2026-07-31
v1
No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

webserver-http-request-indicators-for-cve-2020-0688-exploitation-attempts-7c64e577

title: Webserver Request Matching for CVE-2020-0688 Exploitation Attempt
id: 7e35a2ab-e97d-4563-806b-0a8167a2b459
status: test
description: This rule identifies web requests whose URI query contains the Exchange ecx/default.aspx endpoint along with ASP.NET ViewState parameters (__VIEWSTATEGENERATOR and __VIEWSTATE). Attackers may use crafted ViewState data to target known vulnerable behavior, making these specific query components a useful early signal. The detection relies on webserver telemetry that captures the full request URI query string.
references:
  - https://github.com/Ridter/cve-2020-0688
  - https://github.com/SigmaHQ/sigma/blob/master/rules-emerging-threats/2020/Exploits/CVE-2020-0688/web_cve_2020_0688_exchange_exploit.yml
author: NVISO, Huntrule Team
date: 2020-02-27
modified: 2023-01-02
tags:
  - attack.initial-access
  - attack.t1190
  - cve.2020-0688
  - detection.emerging-threats
logsource:
  category: webserver
detection:
  selection:
    cs-uri-query|contains|all:
      - /ecp/default.aspx
      - __VIEWSTATEGENERATOR=
      - __VIEWSTATE=
  condition: selection
falsepositives:
  - Unknown
level: high
license: DRL-1.1
related:
  - id: 7c64e577-d72e-4c3d-9d75-8de6d1f9146a
    type: derived

Convert

This rule as a query you can run. Uses no unlock credit.

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