Microsoft IIS Connection Strings Decryption

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About the rule

Rule Type

Standard

Rule Description

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.

Severity

Trouble

Rule Requirement

Criteria

Action1: actionname = "Process started" AND (PROCESSNAME endswith "\aspnet_regiis.exe" OR ORIGINALFILENAME = "aspnet_regiis.exe") AND (COMMANDLINE contains "connectionStrings" AND COMMANDLINE contains " -pdf") select Action1.HOSTNAME,Action1.MESSAGE,Action1.COMMANDLINE,Action1.FILE_NAME,Action1.PROCESSNAME,Action1.USERNAME,Action1.PARENTPROCESSNAME

Detection

Execution Mode

realtime

Log Sources

Windows

Author

Tim Rauch, Elastic (idea)