Windows: Detect Microsoft Exchange CVE-2020-0688 exploitation via Eventlog errors

Identifies Exchange Control Panel error events containing a ViewState parameter consistent with CVE-2020-0688 exploitation attempts.

FreeReviewedSigma · High · v5

Product: windows
Service: application
Author: Florian Roth (Nextron Systems), wagga (SigmaHQ), DRL 1.1
Published: 2020-02-29
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 flags Windows application log entries where the Microsoft Exchange Control Panel provider emits an Error event (EventID 4) and the record contains a ViewState parameter marker. An attacker exploiting CVE-2020-0688 may generate crafted Exchange requests that cause these error conditions to be logged. It relies on Windows Application event telemetry including EventID, Provider_Name, Level, and the presence of the '&__VIEWSTATE=' string in the event data.

Reporting behind it

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Windows: Detect Microsoft Exchange CVE-2020-0688 exploitation via Eventlog errors

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.

windows-microsoft-exchange-control-panel-error-with-viewstate-parameter-indicati-d6266bf5

title: "Windows: Detect Microsoft Exchange CVE-2020-0688 exploitation via Eventlog errors"
id: 03a7f2aa-8bc7-48de-96b5-1f8d6b0f86ac
status: test
description: This rule flags Windows application log entries where the Microsoft Exchange Control Panel provider emits an Error event (EventID 4) and the record contains a ViewState parameter marker. An attacker exploiting CVE-2020-0688 may generate crafted Exchange requests that cause these error conditions to be logged. It relies on Windows Application event telemetry including EventID, Provider_Name, Level, and the presence of the '&__VIEWSTATE=' string in the event data.
references:
  - https://www.trustedsec.com/blog/detecting-cve-20200688-remote-code-execution-vulnerability-on-microsoft-exchange-server/
  - https://cyberpolygon.com/materials/okhota-na-ataki-ms-exchange-chast-2-cve-2020-0688-cve-2020-16875-cve-2021-24085/
  - https://github.com/SigmaHQ/sigma/blob/master/rules-emerging-threats/2020/Exploits/CVE-2020-0688/win_vul_cve_2020_0688.yml
author: Florian Roth (Nextron Systems), wagga, Huntrule Team
date: 2020-02-29
modified: 2022-12-25
tags:
  - attack.initial-access
  - attack.t1190
  - cve.2020-0688
  - detection.emerging-threats
logsource:
  product: windows
  service: application
detection:
  selection1:
    EventID: 4
    Provider_Name: MSExchange Control Panel
    Level: Error
  selection2:
    - "&__VIEWSTATE="
  condition: all of selection*
falsepositives:
  - Unknown
level: high
license: DRL-1.1
related:
  - id: d6266bf5-935e-4661-b477-78772735a7cb
    type: derived

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