DLL Load By System Process From Suspicious Locations

Status: test
Severity: medium
Log source: category image_load, product windows
Author: Nasreddine Bencherchali (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects when a system process (i.e. located in system32, syswow64, etc.) loads a DLL from a suspicious location or a location with permissive permissions such as "C:\Users\Public"

MITRE ATT&CK coverage

Tactic	Techniques
Stealth	`T1070` Indicator Removal

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 7: Image loaded

Rule body

title: DLL Load By System Process From Suspicious Locations
id: 9e9a9002-56c4-40fd-9eff-e4b09bfa5f6c
status: test
description: Detects when a system process (i.e. located in system32, syswow64, etc.) loads a DLL from a suspicious location or a location with permissive permissions such as "C:\Users\Public"
references:
    - https://github.com/hackerhouse-opensource/iscsicpl_bypassUAC (Idea)
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-07-17
modified: 2023-09-18
tags:
    - attack.stealth
    - attack.t1070
logsource:
    product: windows
    category: image_load
detection:
    selection:
        Image|startswith: 'C:\Windows\'
        ImageLoaded|startswith:
            # TODO: Add more suspicious paths as you see fit in your env
            - 'C:\Users\Public\'
            - 'C:\PerfLogs\'
    condition: selection
falsepositives:
    - Unknown
level: medium

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    Image|startswith: 'C:\Windows\'
    ImageLoaded|startswith:
        - 'C:\Users\Public\'
        - 'C:\PerfLogs\'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`Image`	starts_with	`C:\Windows\` corpus 2 (sigma 1, elastic 1)	`field:"Image" kind:starts_with value:"C:\Windows\"`
`ImageLoaded`	starts_with	`C:\PerfLogs\` `C:\Users\Public\`	`field:"ImageLoaded" kind:starts_with`