Detection: SAM Database File Access Attempt

Updated Date: 2024-05-22 ID: 57551656-ebdb-11eb-afdf-acde48001122 Author: Michael Haag, Mauricio Velazco, Splunk Type: Hunting Product: Splunk Enterprise Security

Description

The following analytic detects attempts to access the SAM, SYSTEM, or SECURITY database files within the windows\system32\config directory using Windows Security EventCode 4663. This detection leverages Windows Security Event logs to identify unauthorized access attempts. Monitoring this activity is crucial as it indicates potential credential access attempts, possibly exploiting vulnerabilities like CVE-2021-36934. If confirmed malicious, an attacker could extract user passwords, leading to unauthorized access, privilege escalation, and further compromise of the system.

Search

1`wineventlog_security` (EventCode=4663)  ProcessName!=*\\dllhost.exe ObjectName IN ("*\\Windows\\System32\\config\\SAM*","*\\Windows\\System32\\config\\SYSTEM*","*\\Windows\\System32\\config\\SECURITY*") 
2| stats values(AccessList) count by ProcessName ObjectName dest src_user 
3| rename ProcessName as process_name 
4| `sam_database_file_access_attempt_filter`

Data Source

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

Macros Used

Name	Value
wineventlog_security	`eventtype=wineventlog_security OR Channel=security OR source=XmlWinEventLog:Security`
sam_database_file_access_attempt_filter	`search *`

sam_database_file_access_attempt_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
T1003.002	Security Account Manager	Credential Access
T1003	OS Credential Dumping	Credential Access

KillChainPhase.EXPLOITAITON

NistCategory.DE_AE

Cis18Value.CIS_10

APT29

APT41

APT5

Dragonfly

FIN13

GALLIUM

Ke3chang

Threat Group-3390

Wizard Spider

menuPass

APT28

APT32

APT39

Axiom

Leviathan

Poseidon Group

Sowbug

Suckfly

Tonto Team

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

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

Natively, dllhost.exe will access the files. Every environment will have additional native processes that do as well. Filter by process_name. As an aside, one can remove process_name entirely and add Object_Name=*ShadowCopy*.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
The following process $process_name$ accessed the object $ObjectName$ attempting to gain access to credentials on $dest$ by user $src_user$.	80	80	100

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: 3