Detection: Windows DLL Search Order Hijacking Hunt with Sysmon

Updated Date: 2024-05-11 ID: 79c7d1fc-64c7-91be-a616-ccda752efe81 Author: Michael Haag, Splunk Type: Hunting Product: Splunk Enterprise Security

Description

The following analytic identifies potential DLL search order hijacking or DLL sideloading by detecting known Windows libraries loaded from non-standard directories. It leverages Sysmon EventCode 7 to monitor DLL loads and cross-references them with a lookup of known hijackable libraries. This activity is significant as it may indicate an attempt to execute malicious code by exploiting DLL search order vulnerabilities. If confirmed malicious, this could allow attackers to gain code execution, escalate privileges, or maintain persistence within the environment.

1`sysmon` EventCode=7 NOT (process_path IN ("*\\system32\\*", "*\\syswow64\\*","*\\winsxs\\*","*\\wbem\\*")) 
2| lookup hijacklibs library AS loaded_file OUTPUT islibrary 
3| search islibrary = True 
4| stats count min(_time) as firstTime max(_time) as lastTime values(process_name) as process_name by _time dest loaded_file 
5| `windows_dll_search_order_hijacking_hunt_with_sysmon_filter`

Data Source

Name Platform Sourcetype Source Supported App
Sysmon EventID 7 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational' N/A

Macros Used

Name Value
sysmon sourcetype=XmlWinEventLog:Microsoft-Windows-Sysmon/Operational OR source=XmlWinEventLog:Microsoft-Windows-Sysmon/Operational OR source=Syslog:Linux-Sysmon/Operational
windows_dll_search_order_hijacking_hunt_with_sysmon_filter search *
windows_dll_search_order_hijacking_hunt_with_sysmon_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK
+ Kill Chain Phases
+ NIST
+ CIS
- Threat Actors
ID Technique Tactic
T1574.001 DLL Search Order Hijacking Defense Evasion
T1574 Hijack Execution Flow Persistence
KillChainPhase.EXPLOITAITON
KillChainPhase.INSTALLATION
NistCategory.DE_AE
Cis18Value.CIS_10
APT41
Aquatic Panda
BackdoorDiplomacy
Cinnamon Tempest
Evilnum
RTM
Threat Group-3390
Tonto Team
Whitefly
menuPass

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting Value
Disabled true
Cron Schedule 0 * * * *
Earliest Time -70m@m
Latest Time -10m@m
Schedule Window auto
Creates Risk Event False
This configuration file applies to all detections of type hunting.

Implementation

The search is written against the latest Sysmon TA 4.0 https://splunkbase.splunk.com/app/5709. For this specific event ID 7, the sysmon TA will extract the ImageLoaded name to the loaded_file field which is used in the search to compare against the hijacklibs lookup.

Known False Positives

False positives will be present based on paths. Filter or add other paths to the exclusion as needed. Some applications may legitimately load libraries from non-standard paths.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
Potential Windows DLL Search Order Hijacking detected on $dest$ 1 10 10
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation ✅ Passing N/A N/A N/A
Unit ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-Sysmon/Operational xmlwineventlog
Integration ✅ Passing Dataset XmlWinEventLog:Microsoft-Windows-Sysmon/Operational xmlwineventlog

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 5