LoFP / false positives may be present when updates or an administrator adds a new module to iis. monitor and filter as needed.

Techniques

• T1505
• T1505.004

Sample rules

Windows IIS Components New Module Added

• source: splunk
• technicques:
  • T1505
  • T1505.004

Description

The following analytic uses the Windows Event log - Microsoft-IIS-Configuration/Operational - which must be enabled and logged on Windows IIS servers before it can be Splunked. The following analytic identifies newly installed IIS modules. Per Microsoft, IIS modules are not commonly added to a production IIS server, so alerting on this event ID should be enabled.IIS modules can be installed at a global level or at a site level. In detecting malicious IIS modules, it is important to check both the global and site level for unauthorized modules. Regular monitoring of these locations for such modules and comparing against a known good list can help detect and identify malicious IIS modules.

Detection logic

`iis_operational_logs` EventCode=29 
| stats  count min(_time) as firstTime max(_time) as lastTime by OpCode EventCode ComputerName Message 
| rename ComputerName AS dest 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `windows_iis_components_new_module_added_filter`