Detect Rockwell Automation Logix Controllers Insufficient Credential Protection (CVE-2021-22681) in Google Chronicle
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
YARA-L Detection Query
rule cve_2021_22681_rockwell_logix_credential_abuse {
meta:
author = "df00tech"
description = "Detects EtherNet/IP connections to Rockwell Logix controllers potentially exploiting CVE-2021-22681 insufficient credential protection"
severity = "CRITICAL"
priority = "HIGH"
reference = "https://nvd.nist.gov/vuln/detail/CVE-2021-22681"
events:
$network.metadata.event_type = "NETWORK_CONNECTION"
$network.target.port = 44818
(
$network.target.hostname /(?i)(logix|controllogix|compactlogix|guardlogix|rockwell)/ or
$network.target.application = "EtherNet/IP" or
$network.target.application = "CIP"
)
condition:
$network
}Chronicle YARA-L rule detecting network connections to port 44818 (EtherNet/IP) targeting Rockwell Logix controllers, which may indicate exploitation of CVE-2021-22681 credential interception vulnerability.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate engineering workstation connections for controller programming
- Authorized remote access sessions by OEM vendors
- SCADA and historian polling of Logix devices
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
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