Detectionmediumtest

MSSQL Server Failed Logon From External Network

Detects failed logon attempts from clients with external network IP to an MSSQL server. This can be a sign of a bruteforce attack.

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Launch

j4sonCreated Wed Oct 11Updated Wed May 28ebfe73c2-5bc9-4ed9-aaa8-8b54b2b4777dwindows

Log Source

Windowsapplication

ProductWindows← raw: windows

Serviceapplication← raw: application

Definition

Requirements: Must enable MSSQL authentication.

Detection Logic

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: 18456
    filter_main_local_ips:
        Data|contains:
            - 'CLIENT: 10.' # filter_range_IP: 10.0.0.0/8
            - 'CLIENT: 172.16.' # filter_range_IP: 172.16.0.0/12
            - 'CLIENT: 172.17.'
            - 'CLIENT: 172.18.'
            - 'CLIENT: 172.19.'
            - 'CLIENT: 172.20.'
            - 'CLIENT: 172.21.'
            - 'CLIENT: 172.22.'
            - 'CLIENT: 172.23.'
            - 'CLIENT: 172.24.'
            - 'CLIENT: 172.25.'
            - 'CLIENT: 172.26.'
            - 'CLIENT: 172.27.'
            - 'CLIENT: 172.28.'
            - 'CLIENT: 172.29.'
            - 'CLIENT: 172.30.'
            - 'CLIENT: 172.31.'
            - 'CLIENT: 192.168.' # filter_range_IP: 192.168.0.0/16
            - 'CLIENT: 127.' # filter_loop_back: 127.0.0.0/8
            - 'CLIENT: 169.254.' # fileter_link-local_addressing: 169.254.0.0/16
            - 'CLIENT: <local machine>'
    condition: selection and not 1 of filter_main_*