Detect Rockwell Automation Logix Controllers Insufficient Credential Protection (CVE-2021-22681) in Elastic Security
CVE-2021-22681 is an insufficient protection of credentials vulnerability (CWE-522) affecting Rockwell Automation multiple products including Logix controllers. An attacker can intercept or obtain weakly protected credentials used to authenticate with Logix controllers, enabling authentication bypass. This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog and poses critical risk in OT/ICS environments where unauthorized controller access could cause process disruption or physical damage.
MITRE ATT&CK
Elastic Detection Query
sequence by source.ip with maxspan=5m
[network where destination.port == 44818 and
(network.application == "EtherNet/IP" or network.application == "CIP" or destination.port in (44818, 2222, 2221)) and
event.category == "network"]
[network where destination.port == 44818 and
event.category == "network" and
(message like~ "*auth*" or message like~ "*credential*" or message like~ "*login*" or message like~ "*session*")]EQL sequence detection looking for repeated EtherNet/IP connections from the same source to Logix controllers followed by authentication-related activity, indicative of credential harvesting or replay attacks for CVE-2021-22681.
Data Sources
Required Tables
False Positives & Tuning
- Engineering workstations with frequent controller interactions
- Automated SCADA polling sequences
- Network diagnostic tools performing EtherNet/IP enumeration
Other platforms for CVE-2021-22681
Testing Methodology
Validate this detection against 3 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 1EtherNet/IP Controller Enumeration via nmap
Expected signal: Network connection events from the scanning host to port 44818 on multiple destination IPs; IDS alerts for CIP/EtherNet/IP enumeration
- Test 2CIP Session Credential Capture via Wireshark
Expected signal: Passive capture produces no active network events; detection depends on promiscuous mode detection or IDS passive analysis alerts
- Test 3RSLinx Classic Unauthorized Connection Attempt
Expected signal: Windows process creation for RSLinx.exe; network connection from non-engineering workstation to controller port 44818; controller audit log entry for unauthorized connection attempt
Unlock Pro Content
Get the full detection package for CVE-2021-22681 including response playbook, investigation guide, and atomic red team tests.