SAM Registry Hive Handle Request

Metadata

collaborators

[‘Roberto Rodriguez @Cyb3rWard0g’, ‘Jose Rodriguez @Cyb3rPandaH’]

creation date

2019/07/25

modification date

2020/09/20

playbook related

[‘WIN-190625024610’]

Hypothesis

Adversaries might be getting a handle to the SAM database to extract credentials in my environment

Technical Context

Every computer that runs Windows has its own local domain; that is, it has an account database for accounts that are specific to that computer. Conceptually,this is an account database like any other with accounts, groups, SIDs, and so on. These are referred to as local accounts, local groups, and so on. Because computers typically do not trust each other for account information, these identities stay local to the computer on which they were created.

Offensive Tradecraft

Adversaries might use tools like Mimikatz with lsadump::sam commands or scripts such as Invoke-PowerDump to get the SysKey to decrypt Security Account Mannager (SAM) database entries (from registry or hive) and get NTLM, and sometimes LM hashes of local accounts passwords.

In addition, adversaries can use the built-in Reg.exe utility to dump the SAM hive in order to crack it offline.

Additional reading

  • https://github.com/OTRF/ThreatHunter-Playbook/tree/master/docs/library/security_account_manager_database.md

  • https://github.com/OTRF/ThreatHunter-Playbook/tree/master/docs/library/syskey.md

Mordor Test Data

metadata

https://mordordatasets.com/notebooks/small/windows/06_credential_access/SDWIN-190625103712.html

link

https://raw.githubusercontent.com/OTRF/mordor/master/datasets/small/windows/credential_access/host/empire_mimikatz_sam_access.zip

Analytics

Initialize Analytics Engine

from openhunt.mordorutils import *
spark = get_spark()

Download & Process Mordor Dataset

mordor_file = "https://raw.githubusercontent.com/OTRF/mordor/master/datasets/small/windows/credential_access/host/empire_mimikatz_sam_access.zip"
registerMordorSQLTable(spark, mordor_file, "mordorTable")
[+] Processing a Spark DataFrame..
[+] DataFrame Returned !
[+] Temporary SparkSQL View: mordorTable 

Analytic I

Monitor for any handle requested for the SAM registry hive

Data source

Event Provider

Relationship

Event

Windows registry

Microsoft-Windows-Security-Auditing

Process requested access Windows registry key

4656

Windows registry

Microsoft-Windows-Security-Auditing

User requested access Windows registry key

4656

df = spark.sql(
'''
SELECT `@timestamp`, Hostname, SubjectUserName, ProcessName, ObjectName, AccessMask
FROM mordorTable
WHERE LOWER(Channel) = "security"
    AND EventID = 4656
    AND ObjectType = "Key"
    AND lower(ObjectName) LIKE "%sam"
'''
)
df.show(10,False)
+----------+--------+---------------+-----------+----------+----------+
|@timestamp|Hostname|SubjectUserName|ProcessName|ObjectName|AccessMask|
+----------+--------+---------------+-----------+----------+----------+
+----------+--------+---------------+-----------+----------+----------+

Known Bypasses

Idea

Playbook

False Positives

None

Hunter Notes

None

References

  • http://www.harmj0y.net/blog/activedirectory/remote-hash-extraction-on-demand-via-host-security-descriptor-modification/

  • https://github.com/gentilkiwi/mimikatz/wiki/module-~-lsadump

  • https://adsecurity.org/?page_id=1821#LSADUMPSAM