CVE-2017-9148 in FreeRADIUS
Summary
by MITRE
The TLS session cache in FreeRADIUS before 3.0.14 fails to reliably prevent resumption of an unauthenticated session, which allows remote attackers (such as malicious 802.1X supplicants) to bypass authentication via PEAP or TTLS.
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Analysis
by VulDB Data Team • 12/07/2022
The vulnerability identified as CVE-2017-9148 represents a critical flaw in the FreeRADIUS implementation of TLS session resumption mechanisms that directly impacts network authentication security. This issue affects versions of FreeRADIUS prior to 3.0.14 and specifically targets the TLS session cache functionality that is designed to optimize authentication performance by allowing clients to resume previous sessions without re-authenticating. The flaw occurs within the protocol handling layer where the system fails to properly validate session resumption requests, creating a pathway for unauthorized access through manipulated authentication sequences.
The technical root cause of this vulnerability lies in the improper validation of session cache entries during TLS resumption attempts. When a client attempts to resume a previous TLS session, the FreeRADIUS server should verify that the session was originally established with proper authentication credentials. However, the flawed implementation allows sessions to be resumed even when the original authentication was unsuccessful or when the session cache contains entries from unauthenticated connections. This failure to enforce proper session validation creates a persistent security weakness that malicious actors can exploit through specially crafted 802.1X supplicant communications.
The operational impact of this vulnerability extends beyond simple authentication bypass to potentially compromise entire network access control systems. Remote attackers who can establish connections to the FreeRADIUS server can manipulate session resumption requests to gain unauthorized network access through protocols such as PEAP (Protected EAP) and TTLS (Tunneled TLS). This represents a significant threat to enterprise network security as it allows attackers to circumvent authentication mechanisms that are critical for protecting network resources. The vulnerability particularly affects wireless network environments where 802.1X authentication is commonly deployed, making it a serious concern for organizations relying on these security protocols.
Security researchers have classified this vulnerability under CWE-287 which addresses improper authentication issues in network protocols. The flaw aligns with ATT&CK technique T1566 which involves credential harvesting through network protocols, and T1078 which covers valid accounts usage for persistence. Organizations using FreeRADIUS servers in their network infrastructure face significant risk of unauthorized access, privilege escalation, and potential data breaches. The vulnerability demonstrates a fundamental failure in session management security where the system assumes that resumed sessions maintain the same security posture as the original authenticated connections.
The recommended mitigation strategy involves upgrading to FreeRADIUS version 3.0.14 or later, which contains the necessary fixes to properly validate session cache entries during resumption attempts. Administrators should also implement additional monitoring and logging of authentication events to detect anomalous session resumption patterns. Network segmentation and access control measures should be reinforced to limit the potential impact of successful exploitation, while regular security assessments should verify that proper authentication mechanisms remain intact. Organizations should also consider implementing additional authentication layers and continuous monitoring solutions to detect and respond to unauthorized access attempts that may exploit this vulnerability.