SigmaHQ/rules/windows/builtin/win_susp_failed_logons_single_source.yml

title: Multiple Failed Logins with Different Accounts from Single Source System
description: Detects suspicious failed logins with different user accounts from a single source system 
author: Florian Roth
logsource:
    product: windows
    service: security
detection:
    selection1:
        EventID:
            - 529
            - 4625
        UserName: not null
        WorkstationName: not null
    selection2:
        EventID: 4776
        UserName: not null
        Workstation: not null
    timeframe: 24h 
    condition:
        - selection1 | count(UserName) by WorkstationName > 3
        - selection2 | count(UserName) by Workstation > 3
falsepositives:
    - Terminal servers
    - Jump servers
    - Other multiuser systems like Citrix server farms
    - Workstations with frequently changing users 
level: medium
Consistency between format description and examples - description/comment -> title/description - addition of reference 2017-01-10 21:40:59 +00:00			`title: Multiple Failed Logins with Different Accounts from Single Source System`
			`description: Detects suspicious failed logins with different user accounts from a single source system`
Added "logsource" sections and new rule 2017-02-18 23:31:59 +00:00			`author: Florian Roth`
			`logsource:`
Removed lists from log source section 2017-02-19 10:08:23 +00:00			`product: windows`
Windows Built-In rules > LogSource definition 2017-03-05 22:55:52 +00:00			`service: security`
Example Updates 2016-12-27 13:49:54 +00:00			`detection:`
Various rule fixes * Field name: LogonProcess -> LogonProcessName * Field name: Message -> AuditPolicyChanges * Field name: ProcessCommandLine -> CommandLine * Removed Type match in Kerberos RC4 encryption rule Problematic because text representation not unified and audit failures are possibly interesting events * Removed field 'Severity' from rules (Redundant) * Rule decomposition of win_susp_failed_logons_single_source) because of different field names * Field name: SubjectAccountName -> SubjectUserName * Field name: TargetProcess -> TargetImage * Field name: TicketEncryption -> TicketEncryptionType * Field name: TargetFileName -> TargetFilename 2018-03-26 20:53:38 +00:00			`selection1:`
Rule review and cleanup * removed unnecessary one element lists from definitions * converted some lists of one element maps to maps because the resulting OR linkage would cause wrong result. 2017-02-15 22:53:08 +00:00			`EventID:`
			`- 529`
			`- 4625`
			`UserName: not null`
Various rule fixes * Field name: LogonProcess -> LogonProcessName * Field name: Message -> AuditPolicyChanges * Field name: ProcessCommandLine -> CommandLine * Removed Type match in Kerberos RC4 encryption rule Problematic because text representation not unified and audit failures are possibly interesting events * Removed field 'Severity' from rules (Redundant) * Rule decomposition of win_susp_failed_logons_single_source) because of different field names * Field name: SubjectAccountName -> SubjectUserName * Field name: TargetProcess -> TargetImage * Field name: TicketEncryption -> TicketEncryptionType * Field name: TargetFileName -> TargetFilename 2018-03-26 20:53:38 +00:00			`WorkstationName: not null`
			`selection2:`
			`EventID: 4776`
			`UserName: not null`
			`Workstation: not null`
Removed 'last' keyword from 'timeframe' fields 2017-02-28 16:52:40 +00:00			`timeframe: 24h`
Various rule fixes * Field name: LogonProcess -> LogonProcessName * Field name: Message -> AuditPolicyChanges * Field name: ProcessCommandLine -> CommandLine * Removed Type match in Kerberos RC4 encryption rule Problematic because text representation not unified and audit failures are possibly interesting events * Removed field 'Severity' from rules (Redundant) * Rule decomposition of win_susp_failed_logons_single_source) because of different field names * Field name: SubjectAccountName -> SubjectUserName * Field name: TargetProcess -> TargetImage * Field name: TicketEncryption -> TicketEncryptionType * Field name: TargetFileName -> TargetFilename 2018-03-26 20:53:38 +00:00			`condition:`
			`- selection1 \| count(UserName) by WorkstationName > 3`
			`- selection2 \| count(UserName) by Workstation > 3`
Example Updates 2016-12-27 13:49:54 +00:00			`falsepositives:`
Updated examples 2016-12-27 22:09:41 +00:00			`- Terminal servers`
			`- Jump servers`
			`- Other multiuser systems like Citrix server farms`
			`- Workstations with frequently changing users`
Levels to low, medium, high, critical 2017-02-16 17:02:26 +00:00			`level: medium`
Removed lists from log source section 2017-02-19 10:08:23 +00:00