Detection: Non Chrome Process Accessing Chrome Default Dir

Updated Date: 2024-09-30 ID: 81263de4-160a-11ec-944f-acde48001122 Author: Teoderick Contreras, Splunk Type: Anomaly Product: Splunk Enterprise Security

Description

The following analytic detects a non-Chrome process accessing files in the Chrome user default folder. It leverages Windows Security Event logs, specifically event code 4663, to identify unauthorized access attempts. This activity is significant because the Chrome default folder contains sensitive user data such as login credentials, browsing history, and cookies. If confirmed malicious, this behavior could indicate an attempt to exfiltrate sensitive information, often associated with RATs, trojans, and advanced persistent threats like FIN7. Such access could lead to data theft and further compromise of the affected system.

1`wineventlog_security` EventCode=4663 NOT (ProcessName IN ("*\\chrome.exe", "*\\explorer.exe", "*sql*")) ObjectName="*\\Google\\Chrome\\User Data\\Default*" 
2| stats count min(_time) as firstTime max(_time) as lastTime by ObjectName ObjectType ProcessName AccessMask EventCode dest 
3| `security_content_ctime(firstTime)` 
4| `security_content_ctime(lastTime)` 
5| `non_chrome_process_accessing_chrome_default_dir_filter`

Data Source

Name Platform Sourcetype Source
Windows Event Log Security 4663 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:Security'

Macros Used

Name Value
security_content_ctime convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)
non_chrome_process_accessing_chrome_default_dir_filter search *
non_chrome_process_accessing_chrome_default_dir_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
T1555 Credentials from Password Stores Credential Access
T1555.003 Credentials from Web Browsers Credential Access
KillChainPhase.EXPLOITAITON
NistCategory.DE_AE
Cis18Value.CIS_10
APT33
APT39
APT41
Evilnum
FIN6
HEXANE
Leafminer
Malteiro
MuddyWater
OilRig
Stealth Falcon
Volt Typhoon
APT3
APT33
APT37
APT41
Ajax Security Team
FIN6
HEXANE
Inception
Kimsuky
LAPSUS$
Leafminer
Malteiro
Molerats
MuddyWater
OilRig
Patchwork
RedCurl
Sandworm Team
Stealth Falcon
TA505
Volt Typhoon
ZIRCONIUM

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 must ingest Windows Security Event logs and track event code 4663. For 4663, enable "Audit Object Access" in Group Policy. Then check the two boxes listed for both "Success" and "Failure."

Known False Positives

other browser not listed related to chrome may catch by this rule.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
a non chrome browser process $ProcessName$ accessing $ObjectName$ 35 50 70
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation ✅ Passing N/A N/A N/A
Unit ✅ Passing Dataset XmlWinEventLog:Security XmlWinEventLog
Integration ✅ Passing Dataset XmlWinEventLog:Security 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