Microsoft IIS Connection Strings Decryptionedit

Identifies use of aspnet_regiis to decrypt Microsoft IIS connection strings. An attacker with Microsoft IIS web server access via a webshell or alike can decrypt and dump any hardcoded connection strings, such as the MSSQL service account password using aspnet_regiis command.

Rule type: eql

Rule indices:

  • winlogbeat-*
  • logs-windows.*

Severity: high

Risk score: 73

Runs every: 5 minutes

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

Maximum alerts per execution: 33



  • Elastic
  • Host
  • Windows
  • Threat Detection
  • Credential Access

Version: 4 (version history)

Added (Elastic Stack release): 7.10.0

Last modified (Elastic Stack release): 7.12.0

Rule authors: Elastic

Rule license: Elastic License v2

Rule queryedit

process where event.type in ("start", "process_started") and
( : "aspnet_regiis.exe" or
== "aspnet_regiis.exe") and process.args : "connectionStrings" and
process.args : "-pdf"

Threat mappingedit


Rule version historyedit

Version 4 (7.12.0 release)
  • Formatting only
Version 3 (7.11.2 release)
  • Formatting only
Version 2 (7.11.0 release)
  • Updated query, changed from:

    event.category:process and event.type:(start or process_started) and
    ( or or
    winlog.event_data.OriginalFileName:aspnet_regiis.exe) and
    process.args:(connectionStrings and "-pdf")