CVE-2018-13990 in FL SWITCH
Summary
by MITRE
The WebUI of PHOENIX CONTACT FL SWITCH 3xxx, 4xxx, 48xx versions prior to 1.35 is vulnerable to brute-force attacks, because of Improper Restriction of Excessive Authentication Attempts.
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Analysis
by VulDB Data Team • 09/12/2023
The vulnerability identified as CVE-2018-13990 affects the web user interface of PHOENIX CONTACT FL SWITCH series devices including models 3xxx, 4xxx, and 48xx. These industrial network switches operate in critical infrastructure environments where security is paramount for maintaining operational continuity and protecting against unauthorized access. The affected versions prior to 1.35 contain a significant security flaw that undermines the authentication mechanism through improper restriction of excessive authentication attempts, creating a pathway for malicious actors to systematically guess valid credentials through brute-force methodologies.
This authentication weakness stems from the absence of effective rate-limiting mechanisms or account lockout procedures within the web interface implementation. The vulnerability allows attackers to repeatedly attempt login credentials without sufficient restrictions, enabling them to exhaustively test password combinations until they discover valid authentication information. The flaw directly maps to CWE-307, which addresses improper restriction of excessive authentication attempts, a well-documented weakness that has been consistently exploited in various industrial control systems and network devices. The lack of defensive measures such as account lockout after failed attempts, temporary IP blocking, or exponential backoff mechanisms creates an environment where automated credential guessing tools can operate without meaningful obstacles.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it can compromise the integrity and availability of industrial network infrastructure. In critical environments where these switches manage communication between control systems and field devices, unauthorized access could lead to operational disruption, data manipulation, or even physical safety hazards. The vulnerability aligns with ATT&CK technique T1110.003, which covers Brute Force attacks against web applications, and represents a common attack vector that targets industrial control systems. Network administrators and security personnel face the challenge of defending against systematic credential guessing attacks that can be executed continuously without detection or mitigation, potentially leading to persistent unauthorized access to network management interfaces.
Organizations should implement immediate mitigations including firmware updates to version 1.35 or later, which presumably address the authentication weakness through proper rate-limiting mechanisms. Additional defensive measures should include network segmentation to isolate management interfaces, implementing strong access controls with multi-factor authentication, and deploying intrusion detection systems to monitor for suspicious authentication patterns. The vulnerability highlights the critical importance of applying security patches promptly and maintaining comprehensive asset inventories to ensure all industrial network devices receive necessary updates. Security monitoring should specifically track failed authentication attempts and implement automated response mechanisms to block suspicious IP addresses or temporarily disable compromised accounts.