Sigma rule: Microsoft IIS Connection Strings Decryption

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-94a07ec06715, updated 2022-12-30T00:00:00.000Z.

Rule

Title
Microsoft IIS Connection Strings Decryption
Status
test
Level
high
Author
Tim Rauch, Elastic (idea)
Date
2022-09-28
Modified
2022-12-30
File
rules/windows/process_creation/proc_creation_win_iis_connection_strings_decryption.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects 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.

Log source

product
windows
category
process_creation

Detection

selection_name:
    - Image|endswith: '\aspnet_regiis.exe'
    - OriginalFileName: 'aspnet_regiis.exe'
selection_args:
    CommandLine|contains|all:
        - 'connectionStrings'
        - ' -pdf'
condition: all of selection*

False positives (as the rule lists them)

  • Unknown

Tags

  • attack.credential-access
  • attack.t1003

MITRE ATT&CK ids this rule names

References

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_iis_connection_strings_decryption.yml

Sources and licences

  • SigmaHQ

    "Microsoft IIS Connection Strings Decryption" by Tim Rauch, Elastic (idea) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_iis_connection_strings_decryption.yml.
    Licensed under the Detection Rule License (DRL) 1.1: https://github.com/SigmaHQ/Detection-Rule-License

    Detection Rule License (DRL) 1.1

Cite this page

Dragons Eye Ransomware Tracker, "Sigma rule: Microsoft IIS Connection Strings Decryption",
entity page, dataset version ref-94a07ec06715, updated 2022-12-30T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/97dbf6e2-e436-44d8-abee-4261b24d3e41 (accessed 2026-11-03).
Underlying source: SigmaHQ rule 97dbf6e2-e436-44d8-abee-4261b24d3e41, commit ccbb0369507f796db0b0ae6854c8a2be471b9d84.

Pages change. The dataset version identifies the data, but no archive of old versions is kept, so this citation cannot be replayed later.