Detection: Windows Credential Access From Browser Password Store

Updated Date: 2024-05-29 ID: 72013a8e-5cea-408a-9d51-5585386b4d69 Author: Teoderick Contreras, Bhavin Patel Splunk Type: Anomaly Product: Splunk Enterprise Security

Description

The following analytic identifies a possible non-common browser process accessing its browser user data profile. This tactic/technique has been observed in various Trojan Stealers, such as SnakeKeylogger, which attempt to gather sensitive browser information and credentials as part of their exfiltration strategy. Detecting this anomaly can serve as a valuable pivot for identifying processes that access lists of browser user data profiles unexpectedly. This detection uses a lookup file browser_app_list that maintains a list of well known browser applications and the browser paths that are allowed to access the browser user data profiles.

Search

 1`wineventlog_security` EventCode=4663 
 2| stats count by _time object_file_path object_file_name dest process_name process_path process_id EventCode 
 3| lookup browser_app_list browser_object_path as object_file_path OUTPUT browser_process_name isAllowed 
 4| stats count min(_time) as firstTime max(_time) as lastTime values(object_file_name) values(object_file_path)  values(browser_process_name) as browser_process_name by dest process_name process_path process_id EventCode isAllowed 
 5| rex field=process_name "(?<extracted_process_name>[^\\\\]+)$" 
 6| eval isMalicious=if(match(browser_process_name, extracted_process_name), "0", "1") 
 7| where isMalicious=1 and isAllowed="false" 
 8| `security_content_ctime(firstTime)` 
 9| `security_content_ctime(lastTime)` 
10| `windows_credential_access_from_browser_password_store_filter`

Data Source

Name	Platform	Sourcetype	Source	Supported App
Windows Event Log Security 4663	Windows	`'xmlwineventlog'`	`'XmlWinEventLog:Security'`	N/A

Macros Used

Name	Value
security_content_ctime	`convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)`
windows_credential_access_from_browser_password_store_filter	`search *`

windows_credential_access_from_browser_password_store_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
T1012	Query Registry	Discovery

KillChainPhase.EXPLOITAITON

NistCategory.DE_AE

Cis18Value.CIS_10

APT32

APT39

APT41

Chimera

Dragonfly

Fox Kitten

Kimsuky

Lazarus Group

OilRig

Stealth Falcon

Threat Group-3390

Turla

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." This search may trigger on a browser application that is not included in the browser_app_list lookup file.

Known False Positives

The lookup file browser_app_list may not contain all the browser applications that are allowed to access the browser user data profiles. Consider updating the lookup files to add allowed object paths for the browser applications that are not included in the lookup file.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
A non-common browser process $process_name$ accessing browser user data folder on $dest$	25	50	50

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: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: 2