CVE-2017-2342 in Junos
Summary
by MITRE
MACsec feature on Juniper Networks Junos OS 15.1X49 prior to 15.1X49-D100 on SRX300 series does not report errors when a secure link can not be established. It falls back to an unencrypted link. This can happen when MACsec is configured on ports that are not capable of MACsec or when a secure link can not be established. This can mislead customers into believing that a link is secure. On SRX 300 series devices, prior to 15.1X49-D100, MACsec was only supported on control and fabric ports of SRX340 and SRX345 devices. SRX300 and and SRX320 did not have any MACsec capable ports. Configuring MACsec on ports that were not MACsec capable would have resulted in this issue. Affected releases are Juniper Networks Junos OS 15.1X49 prior to 15.1X49-D100 on SRX300 series.
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Analysis
by VulDB Data Team • 01/01/2021
The vulnerability described in CVE-2017-2342 represents a critical security flaw within the MACsec implementation of Juniper Networks Junos OS version 15.1X49 prior to 15.1X49-D100 on SRX300 series devices. This issue fundamentally undermines the integrity of network security by creating a false sense of security through improper error reporting mechanisms. The vulnerability specifically affects devices where MACsec is configured on ports that lack native MACsec capability, leading to a dangerous misconfiguration that can compromise network communications.
The technical flaw manifests in the MACsec feature's inability to properly detect and report failures when establishing secure network links. When MACsec is configured on unsupported ports, particularly on SRX300 series devices which historically lacked MACsec-capable ports, the system fails to indicate that secure communication cannot be established. Instead of alerting administrators to the configuration error, the system silently reverts to unencrypted communication, creating a security blind spot that can persist undetected. This behavior directly violates security best practices and can lead to unauthorized data interception and eavesdropping on network traffic that was expected to be protected.
The operational impact of this vulnerability is significant and multifaceted. Network administrators who configure MACsec on SRX300 series devices may believe their network links are secure when they are actually transmitting data in plaintext. This false assurance can lead to compliance violations, particularly in regulated environments where encryption is mandatory for data protection. The vulnerability affects the core network security posture by allowing attackers to exploit the unencrypted communication channels, potentially gaining access to sensitive information that should have been protected through MACsec encryption. This issue is particularly concerning in environments where network segmentation and encryption are critical security controls.
The vulnerability aligns with CWE-284, which addresses improper access control, as the system fails to properly enforce security policies by not reporting configuration errors that would prevent proper encryption. Additionally, this issue relates to ATT&CK technique T1041, where adversaries can establish persistence and maintain access through network communication channels that should have been secured. Organizations using affected Juniper devices should immediately update to version 15.1X49-D100 or later to resolve this vulnerability. The fix ensures proper error reporting and prevents the fallback to unencrypted communication when MACsec cannot be properly established. Network security teams should conduct comprehensive audits of their MACsec configurations to identify and remediate any instances where MACsec has been incorrectly configured on non-capable ports, ensuring that all network security controls function as intended and provide the expected level of protection.