Detect Brute Force in Sumo Logic CSE
Adversaries may use brute force techniques to gain access to accounts when passwords are unknown or when password hashes are obtained. Without knowledge of the password for an account or set of accounts, an adversary may systematically guess the password using a repetitive or iterative mechanism. Brute forcing passwords can take place via interaction with a service that will check the validity of those credentials or offline against previously acquired credential data, such as password hashes. Threat actors including Fox Kitten, APT38, APT41, OilRig, and Turla have used brute force techniques against RDP, SSH, SMB, and web services.
MITRE ATT&CK
- Tactic
- Credential Access
- Technique
- T1110 Brute Force
- Canonical reference
- https://attack.mitre.org/techniques/T1110/
Sumo Detection Query
_sourceCategory=*windows*security*
| where _raw matches /EventCode=(4624|4625)/
| parse "EventCode=*" as EventCode
| parse "Logon Type:\t*" as LogonType nodrop
| parse "Source Network Address:\t*" as SourceIP nodrop
| parse "Account Name:\t\t*" as TargetAccount nodrop
| parse "Workstation Name:\t*" as Workstation nodrop
| where EventCode in ("4624", "4625")
| where LogonType in ("3", "10")
| eval EventType = if(EventCode == "4625", "Failure", "Success")
| timeslice 10m
| stats
sum(if(EventType == "Failure", 1, 0)) as FailedCount,
sum(if(EventType == "Success", 1, 0)) as SuccessCount,
dcount(TargetAccount) as DistinctTargets,
values(TargetAccount) as TargetAccounts
by _timeslice, SourceIP, Workstation
| where FailedCount >= 10
| eval AttackPattern = if(DistinctTargets > 5, "Password Spray", if(FailedCount >= 20, "Account Brute Force", "Brute Force"))
| eval SuccessAfterFailure = if(SuccessCount > 0, "YES", "NO")
| eval RiskScore = if(SuccessAfterFailure == "YES", 100, if(AttackPattern == "Password Spray" and FailedCount >= 50, 85, if(AttackPattern == "Account Brute Force" and FailedCount >= 100, 75, if(FailedCount >= 20, 60, 40))))
| sort by RiskScore, FailedCountDetects brute force attacks by parsing raw Windows Security Event Log entries for EventCodes 4624 (success) and 4625 (failure) with network logon types (3, 10). Aggregates into 10-minute timeslices per source IP and workstation, requiring at least 10 failures. Classifies attack pattern, computes a 0-100 risk score, and flags success-after-failure windows as potential compromise.
Data Sources
Required Tables
False Positives & Tuning
- Application servers using Windows Integrated Authentication (NTLM/Kerberos) that cache expired session tokens after password rotation, generating a burst of 4625 events before re-authenticating successfully within the same 10-minute window
- Authorized red team or penetration testing engagements where the source IP belongs to a scoped tester, indistinguishable from attacker activity without IP allowlisting
- Mobile device management (MDM) platforms performing bulk certificate or credential refresh across many enrolled devices, with all traffic originating from a single management server IP
Other platforms for T1110
Testing Methodology
Validate this detection against 4 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1RDP Brute Force Simulation with Crowbar
Expected signal: On the target Windows host: Security Event ID 4625 (LogonType=10, RemoteInteractive) for each failed attempt, with IpAddress showing the attacker IP. If lockout policy is enabled and threshold exceeded: Event ID 4740 (account locked out). Network logs: multiple TCP connections to port 3389 from attacker IP in rapid succession.
- Test 2SSH Brute Force with Hydra
Expected signal: On the target Linux host: /var/log/auth.log entries 'Failed password for root from <attacker-ip> port <port> ssh2'. If using auditd: type=USER_AUTH msg entries with res=failed. Sysmon for Linux (if deployed): Event ID 3 (network connection) on the attacker side. SIEM via Syslog forwarder: linux_secure sourcetype or syslog with 'Failed password' pattern.
- Test 3Active Directory Password Spray with PowerShell
Expected signal: On Domain Controller: Security Event ID 4625 (LogonType=3, Network) for each failed account, SubStatus 0xC000006D (wrong password) or 0xC000006A (wrong password for correct username). Caller IP address will be the workstation running the spray. Security Event ID 4771 (Kerberos pre-auth failure) if using Kerberos authentication. Timing will show evenly spaced failures 500ms apart — distinctive automated tool pattern.
- Test 4NTLM Brute Force via SMB with CrackMapExec
Expected signal: Target Windows host: Security Event ID 4625 (LogonType=3, Network, AuthenticationPackageName=NTLM) for each failed credential. Domain Controller: Security Event ID 4776 (NTLM authentication attempt, error code 0xC000006A for wrong password) with Workstation field showing attacker hostname. Network: multiple TCP connections to port 445 (SMB) from attacker IP. CME results show [*] for failure and [+] for success in its output.
References (10)
- https://attack.mitre.org/techniques/T1110/
- https://www.microsoft.com/en-us/security/blog/2021/09/27/foggyweb-targeted-nobelium-malware-leads-to-persistent-backdoor/
- https://learn.microsoft.com/en-us/defender-for-identity/compromised-credentials-alerts
- https://learn.microsoft.com/en-us/azure/active-directory/reports-monitoring/reference-sign-ins-error-codes
- https://www.dragos.com/wp-content/uploads/CRASHOVERRIDE2018.pdf
- https://www.trendmicro.com/en_us/research/20/l/pawn-storm-lack-of-sophistication-as-a-strategy.html
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1110/T1110.md
- https://github.com/SigmaHQ/sigma/tree/master/rules/windows/builtin/security
- https://www.cisa.gov/sites/default/files/2024-09/aa24-249a-foreign-threat-actor-conducting-large-scale-spear-phishing-campaign-with-rdp-attachments.pdf
- https://docs.microsoft.com/en-us/windows/security/threat-protection/auditing/event-4625
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