CVE-2018-0229 in AnyConnect Secure Mobility Client
Summary
by MITRE
A vulnerability in the implementation of Security Assertion Markup Language (SAML) Single Sign-On (SSO) authentication for Cisco AnyConnect Secure Mobility Client for Desktop Platforms, Cisco Adaptive Security Appliance (ASA) Software, and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to establish an authenticated AnyConnect session through an affected device running ASA or FTD Software. The authentication would need to be done by an unsuspecting third party, aka Session Fixation. The vulnerability exists because there is no mechanism for the ASA or FTD Software to detect that the authentication request originates from the AnyConnect client directly. An attacker could exploit this vulnerability by persuading a user to click a crafted link and authenticating using the company's Identity Provider (IdP). A successful exploit could allow the attacker to hijack a valid authentication token and use that to establish an authenticated AnyConnect session through an affected device running ASA or FTD Software. This vulnerability affects the Cisco AnyConnect Secure Mobility Client, and ASA Software and FTD Software configured for SAML 2.0-based SSO for AnyConnect Remote Access VPN that is running on the following Cisco products: 3000 Series Industrial Security Appliances (ISA), ASA 5500 Series Adaptive Security Appliances, ASA 5500-X Series Next-Generation Firewalls, ASA Services Module for Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers, Adaptive Security Virtual Appliance (ASAv), Firepower 2100 Series Security Appliance, Firepower 4100 Series Security Appliance, Firepower 9300 ASA Security Module, FTD Virtual (FTDv). Cisco Bug IDs: CSCvg65072, CSCvh87448.
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Analysis
by VulDB Data Team • 03/03/2023
This vulnerability represents a critical session fixation flaw in Cisco's SAML-based authentication implementation that affects multiple security appliances and client software. The core issue stems from the absence of proper origin validation mechanisms within the Adaptive Security Appliance and Firepower Threat Defense software when processing SAML 2.0 authentication requests. The vulnerability is classified under CWE-384 as Session Fixation, where an attacker can manipulate the authentication process by tricking users into using a pre-established session token. The flaw specifically impacts the AnyConnect Secure Mobility Client when configured with SAML 2.0-based SSO authentication, creating a scenario where an unauthenticated remote attacker can establish an authenticated session through the affected devices.
The technical exploitation occurs when an attacker crafts a malicious link that, when clicked by an unsuspecting user, triggers a SAML authentication flow through the victim's browser. The attack leverages the fact that the ASA or FTD software cannot distinguish between legitimate authentication requests originating directly from the AnyConnect client versus those initiated through a crafted web interface. This lack of proper session validation allows the attacker to capture and reuse valid authentication tokens, effectively hijacking the authentication process. The vulnerability is particularly dangerous because it requires no prior authentication credentials from the attacker and relies entirely on social engineering to convince a legitimate user to interact with the malicious link.
The operational impact of this vulnerability is severe as it allows attackers to gain unauthorized access to corporate networks through legitimate authentication mechanisms. Once successfully exploited, the attacker can establish authenticated AnyConnect sessions that provide full access to network resources as if they were legitimate users. This creates a persistent threat vector that can be used for data exfiltration, lateral movement, and other malicious activities within the compromised network. The vulnerability affects a wide range of Cisco security appliances including 3000 Series ISAs, ASA 5500 series appliances, ASA 5500-X series firewalls, and various Firepower appliances, making it a significant concern for organizations using these platforms for remote access security.
Mitigation strategies should focus on implementing proper session management controls and origin validation mechanisms within the SAML authentication flow. Organizations should consider disabling SAML 2.0-based SSO for AnyConnect if not strictly required, or implementing additional authentication controls such as multi-factor authentication to reduce the risk. Network administrators should also monitor for unusual authentication patterns and implement proper network segmentation to limit the potential damage from successful exploitation. The vulnerability aligns with ATT&CK technique T1566 for Phishing and T1078 for Valid Accounts, as it combines social engineering with authentication bypass techniques. Cisco has released patches addressing this vulnerability through their security advisory process, and organizations should immediately apply the relevant software updates to protect their infrastructure from this session fixation attack vector.