CVE-2019-1714 in ASA
Summary
by MITRE
A vulnerability in the implementation of Security Assertion Markup Language (SAML) 2.0 Single Sign-On (SSO) for Clientless SSL VPN (WebVPN) and AnyConnect Remote Access VPN in Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to successfully establish a VPN session to an affected device. The vulnerability is due to improper credential management when using NT LAN Manager (NTLM) or basic authentication. An attacker could exploit this vulnerability by opening a VPN session to an affected device after another VPN user has successfully authenticated to the affected device via SAML SSO. A successful exploit could allow the attacker to connect to secured networks behind the affected device.
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Analysis
by VulDB Data Team • 09/12/2023
The vulnerability identified as CVE-2019-1714 represents a critical flaw in Cisco's Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) software implementations of SAML 2.0 Single Sign-On functionality. This security weakness specifically affects Clientless SSL VPN (WebVPN) and AnyConnect Remote Access VPN services, creating a significant attack vector that could compromise network security. The vulnerability stems from inadequate credential management practices during authentication processes, particularly when utilizing NT LAN Manager (NTLM) or basic authentication methods within the SAML framework.
The technical implementation flaw manifests in the improper handling of authentication state management within the affected Cisco products. When users authenticate successfully through SAML SSO, the system fails to properly invalidate or reset authentication credentials, allowing subsequent unauthorized access attempts to leverage the existing authenticated session state. This credential management failure occurs at the application layer where SAML assertions are processed and validated, creating a persistent security gap that can be exploited by attackers without requiring valid credentials or authentication tokens. The vulnerability specifically impacts the session establishment process where the system should enforce strict authentication boundaries but instead permits session reuse under compromised conditions.
From an operational perspective, this vulnerability creates a severe risk for organizations relying on Cisco ASA and FTD devices for network access control and security enforcement. Attackers can exploit this weakness by initiating a VPN session after a legitimate user has authenticated through SAML SSO, effectively hijacking the authentication state to gain unauthorized network access. The implications extend beyond simple unauthorized access, as successful exploitation allows attackers to traverse secured networks behind the affected devices, potentially leading to data exfiltration, lateral movement, and privilege escalation within the network infrastructure. This vulnerability directly impacts the principle of least privilege and can undermine the entire security architecture built around these devices.
The attack surface for this vulnerability aligns with several ATT&CK framework techniques including T1078 Valid Accounts for initial access and T1021 Remote Services for maintaining persistent network presence. This weakness can be categorized under CWE-287 Improper Handling of Authentication Errors, which specifically addresses improper credential management and authentication state handling. Organizations using these Cisco products face significant risk of unauthorized network access, potential data breaches, and compromise of sensitive network resources. The vulnerability's impact is particularly concerning in environments where sensitive data resides behind the affected devices, as it could enable attackers to bypass traditional network security controls and gain direct access to protected resources.
Mitigation strategies for CVE-2019-1714 should prioritize immediate patch application from Cisco, specifically addressing the authentication state management issues in the SAML 2.0 implementation. Organizations should implement network segmentation to limit the potential impact of successful exploitation and monitor VPN session logs for unusual authentication patterns or unauthorized access attempts. Additional protective measures include disabling unnecessary SAML authentication methods when not required, implementing strict access controls for VPN services, and establishing robust monitoring protocols to detect anomalous session establishment patterns. Network administrators should also consider implementing multi-factor authentication mechanisms to add additional layers of security beyond the vulnerable SAML implementation, while maintaining comprehensive audit trails to track all authentication events and session establishment activities.