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Windows IIS connection string decryption via aspnet_regiis -pdf

Flags aspnet_regiis.exe runs that target IIS connectionStrings for decryption using -pdf.

FreeReviewedSigma · High · v2
Product
windows
Category
process_creation
Author
Tim Rauch, Elastic (idea) (SigmaHQ), DRL 1.1
Published
2022-09-28
Updated
2026-07-31
AnalysisDetection

ATT&CK techniques

Cred Access

  1. Recon

  2. Resource Dev

  3. Initial Access

  4. Execution

  5. Persistence

  6. Priv Esc

  7. Defense Evasion

  8. Cred Access

  9. Discovery

  10. Lateral Movement

  11. Collection

  12. C2

  13. Exfiltration

  14. Impact

What it detects

This rule flags execution of aspnet_regiis.exe with arguments indicating connectionStrings decryption and PDF output. Attackers who gain IIS server access can use this functionality to extract or decrypt hardcoded connection strings, potentially including sensitive credentials. It relies on Windows process creation telemetry capturing the process image and command-line arguments.

Reporting behind it

Related detections9 linkedT1003 — drag to rearrange
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Suspicious Mimilite Credential Dumper Execution Writing KB-Named Output
Malicious InternalMonologue NTLM Downgrade Execution via process_creation
Suspicious Modification of msDS-KeyCredentialLink for Shadow Credential Abuse
Possible OxideHarvest Stealer Execution via Combined Short Flag Set
Suspicious Credential Dump Attempt via Task Manager (via process_creation)
Suspicious Ivanti EPMM Database Dump via mysqldump with .mifpp Credentials (via process_creation)
Suspicious Credential Dump via lsa.exe Debug Output
Malicious Wdigest Authentication Enabled - Reg via Command (via process_creation)
Windows IIS connection string decryption via aspnet_regiis -pdf
Pivot detection · T1003 · 9 related

Changelog

v2
  1. v2
    Candidate ingested via manual entry.2026-07-31
  2. 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.