DLL Load via LSASS

Status: test
Severity: high
Log source: category registry_event, product windows
Author: Florian Roth (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects a method to load DLL via LSASS process using an undocumented Registry key

MITRE ATT&CK coverage

Tactic	Techniques
Persistence	`T1547.008` Boot or Logon Autostart Execution: LSASS Driver
Privilege Escalation	`T1547.008` Boot or Logon Autostart Execution: LSASS Driver

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 12: RegistryEvent (Object create and delete)
Sysmon	Event ID 13: RegistryEvent (Value Set)
Sysmon	Event ID 14: RegistryEvent (Key and Value Rename)

Rule body

title: DLL Load via LSASS
id: b3503044-60ce-4bf4-bbcb-e3db98788823
status: test
description: Detects a method to load DLL via LSASS process using an undocumented Registry key
references:
    - https://blog.xpnsec.com/exploring-mimikatz-part-1/
    - https://twitter.com/SBousseaden/status/1183745981189427200
author: Florian Roth (Nextron Systems)
date: 2019-10-16
modified: 2022-04-21
tags:
    - attack.privilege-escalation
    - attack.execution
    - attack.persistence
    - attack.t1547.008
logsource:
    category: registry_event
    product: windows
detection:
    selection:
        TargetObject|contains:
            - '\CurrentControlSet\Services\NTDS\DirectoryServiceExtPt'
            - '\CurrentControlSet\Services\NTDS\LsaDbExtPt'
    filter_domain_controller:
        Image: 'C:\Windows\system32\lsass.exe'
        Details:
            - '%%systemroot%%\system32\ntdsa.dll'
            - '%%systemroot%%\system32\lsadb.dll'
    condition: selection and not 1 of filter_*
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: `condition`

selection and not 1 of filter_*

Stage 1: `selection`

selection:
    TargetObject|contains:
        - '\CurrentControlSet\Services\NTDS\DirectoryServiceExtPt'
        - '\CurrentControlSet\Services\NTDS\LsaDbExtPt'

Stage 2: `not filter_domain_controller`

filter_domain_controller:
    Image: 'C:\Windows\system32\lsass.exe'
    Details:
        - '%%systemroot%%\system32\ntdsa.dll'
        - '%%systemroot%%\system32\lsadb.dll'

Exclusions

The rule actively suppresses these predicates.

Field	Kind	Excluded values	Search
`Details`	eq	`%%systemroot%%\system32\lsadb.dll`	`excludes:Details` `field:"Details" value:"%%systemroot%%\system32\lsadb.dll"`
`Details`	eq	`%%systemroot%%\system32\ntdsa.dll`	`excludes:Details` `field:"Details" value:"%%systemroot%%\system32\ntdsa.dll"`
`Image`	eq	`C:\Windows\system32\lsass.exe`	`excludes:Image` `field:"Image" value:"C:\Windows\system32\lsass.exe"`

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`TargetObject`	match	`\CurrentControlSet\Services\NTDS\DirectoryServiceExtPt` `\CurrentControlSet\Services\NTDS\LsaDbExtPt`	`field:"TargetObject" kind:match`

DLL Load via LSASS

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Stage 0: condition

Stage 1: selection

Stage 2: not filter_domain_controller

Exclusions

Indicators

Stage 0: `condition`

Stage 1: `selection`

Stage 2: `not filter_domain_controller`