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Detection rules › Sigma

MSSQL Disable Audit Settings

Status
test
Severity
high
Log source
product windows, service application
Author
Nasreddine Bencherchali (Nextron Systems)
Source
github.com/SigmaHQ/sigma

Detects when an attacker calls the "ALTER SERVER AUDIT" or "DROP SERVER AUDIT" transaction in order to delete or disable audit logs on the server

MITRE ATT&CK coverage

TacticTechniques
Defense ImpairmentNo specific technique

Event coverage

ProviderEvent
MSSQLSERVEREvent ID 33205

Rule body yaml

title: MSSQL Disable Audit Settings
id: 350dfb37-3706-4cdc-9e2e-5e24bc3a46df
status: test
description: Detects when an attacker calls the "ALTER SERVER AUDIT" or "DROP SERVER AUDIT" transaction in order to delete or disable audit logs on the server
references:
    - https://www.netspi.com/blog/technical/network-penetration-testing/sql-server-persistence-part-1-startup-stored-procedures/
    - https://learn.microsoft.com/en-us/sql/t-sql/statements/drop-server-audit-transact-sql?view=sql-server-ver16
    - https://learn.microsoft.com/en-us/sql/t-sql/statements/alter-server-audit-transact-sql?view=sql-server-ver16
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-07-13
modified: 2024-06-26
tags:
    - attack.defense-impairment
logsource:
    product: windows
    service: application
    definition: 'Requirements: MSSQL audit policy must be enabled in order to receive this event in the application log'
    # warning: The 'data' field used in the detection section is the container for the event data as a whole. You may have to adapt the rule for your backend accordingly
detection:
    selection:
        Provider_Name|contains: 'MSSQL' # Note: We use contains to account for other third party providers - See https://github.com/SigmaHQ/sigma/issues/4876
        EventID: 33205
        Data|contains:
            - 'statement:ALTER SERVER AUDIT'
            - 'statement:DROP SERVER AUDIT'
    condition: selection
falsepositives:
    - This event should only fire when an administrator is modifying the audit policy. Which should be a rare occurrence once it's set up
level: high

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    Provider_Name|contains: 'MSSQL'
    EventID: 33205
    Data|contains:
        - 'statement:ALTER SERVER AUDIT'
        - 'statement:DROP SERVER AUDIT'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
Datamatch
  • statement:ALTER SERVER AUDIT
  • statement:DROP SERVER AUDIT
Provider_Namematch
  • MSSQL corpus 7 (sigma 7)