Detection: Windows Process Injection into Notepad

Updated Date: 2024-09-30 ID: b8340d0f-ba48-4391-bea7-9e793c5aae36 Author: Michael Haag, Splunk Type: Anomaly Product: Splunk Enterprise Security

Description

The following analytic detects process injection into Notepad.exe using Sysmon EventCode 10. It identifies suspicious GrantedAccess requests (0x40 and 0x1fffff) to Notepad.exe, excluding common system paths like System32, Syswow64, and Program Files. This behavior is often associated with the SliverC2 framework by BishopFox. Monitoring this activity is crucial as it may indicate an initial payload attempting to execute malicious code within Notepad.exe. If confirmed malicious, this could allow attackers to execute arbitrary code, potentially leading to privilege escalation or persistent access within the environment.

1`sysmon` EventCode=10 TargetImage IN (*\\notepad.exe) NOT (SourceImage IN ("*\\system32\\*","*\\syswow64\\*","*\\Program Files\\*")) GrantedAccess IN ("0x40","0x1fffff") 
2| stats count min(_time) as firstTime max(_time) as lastTime by dest SourceImage TargetImage GrantedAccess CallTrace 
3| `security_content_ctime(firstTime)` 
4| `security_content_ctime(lastTime)` 
5| `windows_process_injection_into_notepad_filter`

Data Source

Name Platform Sourcetype Source
Sysmon EventID 10 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'

Macros Used

Name Value
security_content_ctime convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)
windows_process_injection_into_notepad_filter search *
windows_process_injection_into_notepad_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
T1055 Process Injection Defense Evasion
T1055.002 Portable Executable Injection Privilege Escalation
KillChainPhase.EXPLOITAITON
NistCategory.DE_AE
Cis18Value.CIS_10
APT32
APT37
APT41
APT5
Cobalt Group
Kimsuky
PLATINUM
Silence
TA2541
Turla
Wizard Spider
Gorgon Group
Rocke

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 True
This configuration file applies to all detections of type anomaly. These detections will use Risk Based Alerting.

Implementation

To successfully implement this search, you need to be ingesting logs with the process name, parent process, and command-line executions from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA.

Known False Positives

False positives may be present based on SourceImage paths. If removing the paths is important, realize svchost and many native binaries inject into notepad consistently. Restrict or tune as needed.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
An instance of $SourceImage$ injecting into $TargetImage$ was identified on endpoint $dest$. 32 40 80
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: 4