IIS Native-Code Module Command Line Installation

Severity: medium
Author: Florian Roth (Nextron Systems)
Source: upstream

Detects suspicious IIS native-code module installations via command line

MITRE ATT&CK coverage

Tactic	Techniques
Persistence	`T1505.003` Server Software Component: Web Shell

Event coverage

Provider	Event ID	Title
Sysmon	1	Process creation

Stages and Predicates

Stage 1: `all of selection_img`

or:
Image|endswith: '\appcmd.exe'
OriginalFileName: appcmd.exe

Stage 2: `all of selection_cli`

CommandLine|contains: '-name:'
CommandLine|contains: install
CommandLine|contains: module

Stage 3: `not 1 of filter_iis_setup`

ParentImage: 'C:\Windows\System32\inetsrv\iissetup.exe'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

Field	Kind	Values
`CommandLine`	match	`-name:` `install` corpus 4 (sigma 4) `module`
`Image`	ends_with	`\appcmd.exe` corpus 4 (sigma 4)
`OriginalFileName`	eq	`appcmd.exe` corpus 4 (sigma 4)
`ParentImage`	eq	`C:\Windows\System32\inetsrv\iissetup.exe`