Detect Remote Desktop Protocol in CrowdStrike LogScale
Adversaries may use Valid Accounts to log into a computer using the Remote Desktop Protocol (RDP). RDP is a common feature in Windows that allows interactive graphical sessions on remote systems. Threat actors including Kimsuky, INC Ransom, Volt Typhoon, Wizard Spider, BlackByte, Akira, and FIN7 have all leveraged RDP for lateral movement. Adversaries typically acquire credentials via Credential Access techniques, then use RDP to expand access to additional systems, deploy ransomware interactively, or establish persistence via Accessibility Features.
MITRE ATT&CK
- Tactic
- Lateral Movement
- Technique
- T1021 Remote Services
- Sub-technique
- T1021.001 Remote Desktop Protocol
- Canonical reference
- https://attack.mitre.org/techniques/T1021/001/
LogScale Detection Query
// RDP brute force detection: 5+ failures per source IP per 5-minute bucket
#event_simpleName=UserLogonFailed2 LogonType=10
| where RemoteIP != "127.0.0.1"
and RemoteIP != "::1"
and RemoteIP != "-"
and isNotNull(RemoteIP)
| bucket(span=5min, field=[@timestamp], as=TimeBucket)
| groupBy([RemoteIP, ComputerName, TimeBucket], function=[
count(as=FailureCount),
collect(UserName, limit=20, as=AttemptedAccounts)
])
| where FailureCount >= 5
| eval AlertType = "RDP_BruteForce"
| sort(FailureCount, order=desc)
// Successful RDP logon to sensitive host or by privileged account
// (run as a separate query and union results for alerting)
#event_simpleName=UserLogon LogonType=10
| where RemoteIP != "127.0.0.1"
and RemoteIP != "::1"
and RemoteIP != "-"
and isNotNull(RemoteIP)
| eval SensitiveHost = if(match("(?i)(^dc|dc01|pdc|domain.controller)", ComputerName), "true", "false")
| eval PrivAccount = if(match("(?i)(admin|administrator|svc_|service)", UserName), "true", "false")
| where SensitiveHost = "true" or PrivAccount = "true"
| eval RiskScore = if(SensitiveHost = "true", 10, 0) + if(PrivAccount = "true", 5, 0)
| groupBy([RemoteIP, ComputerName, UserName, SensitiveHost, PrivAccount, RiskScore], function=[
count(as=EventCount),
min(@timestamp, as=FirstSeen),
max(@timestamp, as=LastSeen)
])
| eval AlertType = "RDP_SensitiveTarget"
| sort(RiskScore, order=desc)Detects T1021.001 RDP lateral movement in CrowdStrike Falcon LogScale (CQL) via two complementary queries against Falcon telemetry. Query 1 uses UserLogonFailed2 events with LogonType=10 (RDP), bucketed in 5-minute windows by source IP, alerting when a single IP generates 5+ failures — indicating credential stuffing or brute force. Query 2 uses UserLogon events with LogonType=10 to detect successful RDP sessions targeting sensitive hosts (DC/PDC naming convention) or using privileged/service accounts, with a risk score for triage. Both queries filter loopback and null source IPs.
Data Sources
Required Tables
False Positives & Tuning
- IT administrators using CrowdStrike-monitored endpoints to RDP into domain controllers during incident response or routine maintenance — will trigger the sensitive host rule.
- Password reset workflows where users fail authentication multiple times before successfully logging in via RDP, particularly after Active Directory password changes propagate.
- Network Access Control (NAC) or endpoint compliance systems that perform periodic RDP health checks against servers, generating repeated logon events from a shared scanner IP.
Other platforms for T1021.001
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 1RDP Connection to Remote Host
Expected signal: Sysmon Event ID 1: Process Create with Image=mstsc.exe, CommandLine='/v:127.0.0.1 /admin'. Sysmon Event ID 3: Network Connection to port 3389. Security Event ID 4624 (LogonType=10) on the target if RDP is enabled. Event ID 1149 in TerminalServices-RemoteConnectionManager log.
- Test 2Enable RDP and Create RDP-Accessible User
Expected signal: Sysmon Event ID 13 (Registry Value Set) for HKLM\System\CurrentControlSet\Control\Terminal Server\fDenyTSConnections. Sysmon Event ID 1 (Process Create) for net.exe with 'Remote Desktop Users' in command line. Security Event ID 4732 (member added to security-enabled local group). Security Event ID 4657 (registry value modified).
- Test 3Simulate RDP Brute Force (Authentication Failures)
Expected signal: Security Event ID 4625 (Logon Failure, LogonType=10) for each failed attempt. Microsoft-Windows-TerminalServices-RemoteConnectionManager/Operational Event ID 261. After 6 failures, detection threshold should fire.
- Test 4RDP Tunnel via NetSH Port Proxy
Expected signal: Sysmon Event ID 1: Process Create for netsh.exe with 'portproxy' and 'add' in command line. Registry change at HKLM\SYSTEM\CurrentControlSet\Services\PortProxy. Security Event ID 4688 for netsh.exe. Sysmon Event ID 12/13 for registry modification.
References (8)
- https://attack.mitre.org/techniques/T1021/001/
- https://technet.microsoft.com/en-us/windowsserver/ee236407.aspx
- https://learn.microsoft.com/en-us/defender-endpoint/advanced-hunting-securityevent-table
- https://docs.microsoft.com/en-us/windows/security/threat-protection/auditing/event-4624
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1021.001/T1021.001.md
- https://www.crowdstrike.com/blog/adversary-tricks-crowdstrike-treats/
- https://www.mandiant.com/resources/blog/fin12-ransomware-intrusion-actor-partnering-trickbot
- https://www.cisa.gov/news-events/cybersecurity-advisories/aa24-038a
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