Detect Default Accounts in CrowdStrike LogScale
Adversaries may obtain and abuse credentials of a default account as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Default accounts are those built into an OS (e.g., Guest or Administrator on Windows, root on Linux), preset on network devices/appliances, or created automatically by software integrations (e.g., vpxuser on ESXi when joined to vCenter). Adversaries exploit organizations that fail to disable, rename, or change the passwords of these accounts post-installation.
MITRE ATT&CK
- Technique
- T1078 Valid Accounts
- Sub-technique
- T1078.001 Default Accounts
- Canonical reference
- https://attack.mitre.org/techniques/T1078/001/
LogScale Detection Query
union(
{
(#event_simpleName=UserLogon OR #event_simpleName=UserLogonFailed2)
| UserName = /(?i)^(administrator|guest|defaultaccount|defaultuser|admin|root|vpxuser|dcadmin|sysadmin|service|support|user|test|demo|operator|sa|netadmin)$/
| eval(EventType="DefaultAccountLogon")
},
{
#event_simpleName=ProcessRollup2
| CommandLine = regex("(?i)(net\s+user\s+(defaultaccount|guest|administrator)\s+/active:yes|net\s+localgroup\s+administrators\s+(guest|defaultaccount|administrator))")
| eval(EventType="DefaultAccountActivation")
}
)
| table([_time, ComputerName, UserName, UserPrincipalName, LogonType_decimal, RemoteIP, CommandLine, EventType, #event_simpleName])
| sort(field=_time, order=desc)CrowdStrike LogScale (Humio) query using Falcon sensor telemetry. Uses union() to combine two detection branches: the first matches UserLogon and UserLogonFailed2 events where the UserName field matches known default built-in account names via case-insensitive regex filter; the second matches ProcessRollup2 (process creation) events where CommandLine contains net user or net localgroup commands activating or elevating default accounts. Both branches are tagged with an EventType label via eval() before being merged and sorted.
Data Sources
Required Tables
False Positives & Tuning
- IT staff accessing servers using local Administrator accounts during domain-disconnected maintenance windows, disaster recovery procedures, or when domain controllers are unreachable.
- Security operations teams running authorized adversary simulation (red team) or purple team exercises using default credentials against scoped target systems within approved test windows.
- Automated Ansible, Chef, or Puppet configuration management runs that authenticate with local service or admin accounts to complete node configuration tasks during deployment pipelines.
Other platforms for T1078.001
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 1Enable and Use Built-in DefaultAccount via PowerShell (Magic Hound TTP)
Expected signal: Sysmon Event ID 1: Process Create with CommandLine containing 'net user DefaultAccount /active:yes'. Windows Security Event ID 4722 (User Account Enabled) with TargetUserName=DefaultAccount. Windows Security Event ID 4725 (User Account Disabled) after cleanup. Security Event ID 4688 (process creation) if command-line auditing is enabled.
- Test 2Enable Built-in Guest Account and Verify Access
Expected signal: Windows Security Event ID 4722 (User Account Enabled) with TargetUserName=Guest. Windows Security Event ID 4688 or Sysmon Event ID 1 with CommandLine 'net user Guest /active:yes'. Security Event ID 4625 if subsequent logon attempt is made. Event ID 4725 on cleanup.
- Test 3Authenticate Using Built-in Administrator Account via Net Use (HyperStack-style IPC$ Access)
Expected signal: Windows Security Event ID 4648 (Logon using explicit credentials) with TargetUserName=Administrator and TargetServerName=127.0.0.1. Windows Security Event ID 4624 (logon type 3 - Network) or 4625 (failed logon) on the target host. Sysmon Event ID 1 with CommandLine 'net use \\127.0.0.1\IPC$'. Sysmon Event ID 3 (network connection) to port 445.
- Test 4Simulate Default Service Account Logon via Scheduled Task
Expected signal: Windows Security Event ID 4698 (Scheduled Task Created) with task name 'DefaultAccountTest'. Windows Security Event ID 4624 (SYSTEM logon type 5) when task executes. Sysmon Event ID 1 for schtasks.exe and cmd.exe processes. Sysmon Event ID 11 (File Created) for the output file in TEMP. Security Event ID 4699 (Scheduled Task Deleted) on cleanup.
References (14)
- https://attack.mitre.org/techniques/T1078/001/
- https://docs.microsoft.com/en-us/windows/security/identity-protection/access-control/local-accounts
- https://docs.aws.amazon.com/IAM/latest/UserGuide/id_root-user.html
- https://cloud.google.com/blog/topics/threat-intelligence/vmware-esxi-zero-day-bypass/
- https://pentera.io/blog/information-disclosure-in-vmware-vcenter/
- https://www.microsoft.com/security/blog/2020/04/02/attack-matrix-kubernetes/
- https://github.com/rapid7/metasploit-framework/tree/master/modules/exploits/linux/ssh
- https://www.cisa.gov/news-events/cybersecurity-advisories/aa24-249a
- https://www.sygnia.co/blog/elephant-beetle-an-organized-financial-threat/
- https://thedfirreport.com/2021/11/15/exchange-exploit-leads-to-domain-wide-ransomware/
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1078.001/T1078.001.md
- https://learn.microsoft.com/en-us/windows/security/threat-protection/auditing/event-4624
- https://learn.microsoft.com/en-us/windows/security/threat-protection/auditing/event-4625
- https://learn.microsoft.com/en-us/windows/security/threat-protection/auditing/event-4722
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