CVE-2013-5511 in ASA
Summary
by MITRE
The Adaptive Security Device Management (ASDM) remote-management feature in Cisco Adaptive Security Appliance (ASA) Software 8.2.x before 8.2(5.46), 8.3.x before 8.3(2.39), 8.4.x before 8.4(6), 8.5.x before 8.5(1.18), 8.6.x before 8.6(1.12), 8.7.x before 8.7(1.7), 9.0.x before 9.0(3.1), and 9.1.x before 9.1(2.6) does not properly implement the authentication-certificate option, which allows remote attackers to bypass authentication via a TCP session to an ASDM interface, aka Bug ID CSCuh44815.
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Analysis
by VulDB Data Team • 05/26/2021
The vulnerability described in CVE-2013-5511 represents a critical authentication bypass flaw within Cisco Adaptive Security Appliance (ASA) software versions across multiple release branches. This issue specifically targets the Adaptive Security Device Management (ASDM) remote-management feature, which serves as the primary interface for administrators to configure and manage ASA security appliances. The vulnerability stems from improper implementation of the authentication-certificate option, creating a pathway for unauthorized remote attackers to gain access to the ASDM interface without proper authentication credentials. This flaw affects a wide range of ASA software versions including 8.2.x through 9.1.x releases, making it a widespread concern across multiple generations of Cisco security appliances. The vulnerability is particularly dangerous because it allows attackers to establish TCP sessions directly to the ASDM interface and bypass the normal authentication mechanisms that should protect administrative access to these critical network security devices.
The technical implementation of this vulnerability involves a flaw in how the ASA software handles certificate-based authentication for ASDM access. When administrators configure the authentication-certificate option, the system should enforce strict certificate validation and authentication requirements before granting access to the management interface. However, the flawed implementation allows attackers to establish TCP connections to the ASDM port without presenting valid authentication credentials or certificates. This creates a scenario where an attacker can potentially access the administrative interface through a direct network connection, circumventing the intended authentication flow. The vulnerability operates at the network protocol level, specifically targeting the TCP session establishment process for ASDM connections, which is categorized under CWE-287 - Improper Authentication. The flaw essentially creates a backdoor access mechanism that bypasses the normal certificate validation procedures that should occur during the initial connection handshake.
The operational impact of this vulnerability extends far beyond simple unauthorized access, as it fundamentally compromises the security posture of networks protected by affected ASA appliances. An attacker who successfully exploits this vulnerability gains full administrative access to the ASA device, enabling them to modify firewall rules, access network traffic, change system configurations, and potentially pivot to other network segments. This access can be particularly devastating in enterprise environments where ASA appliances serve as primary network security gateways, as it allows attackers to manipulate the core security policies that protect the organization's network infrastructure. The vulnerability also impacts compliance requirements, as it creates unauthorized access points that can be exploited to bypass security controls and potentially evade audit mechanisms. From an ATT&CK perspective, this vulnerability maps to T1078 - Valid Accounts and T1566 - Phishing, as it allows adversaries to establish unauthorized administrative sessions and potentially escalate privileges through compromised management interfaces. The impact is particularly severe because it affects multiple ASA software versions simultaneously, meaning that organizations with legacy deployments across various release branches remain vulnerable.
Organizations affected by this vulnerability should implement immediate mitigations to protect their network security infrastructure. The primary recommendation is to upgrade to patched versions of ASA software that address the authentication certificate implementation flaw, specifically targeting the version numbers mentioned in the vulnerability description. Cisco released patches for all affected software versions, and organizations should prioritize upgrading their ASA appliances to the latest secure releases. Network segmentation and access control measures should be implemented to limit direct access to ASDM ports from untrusted networks, reducing the attack surface for exploitation attempts. Additionally, organizations should monitor their network traffic for unusual connections to ASDM ports and implement intrusion detection systems that can identify potential exploitation attempts. The vulnerability highlights the importance of proper certificate management and authentication implementation in security appliances, emphasizing that administrative interfaces must maintain strict authentication controls to prevent unauthorized access. Security teams should also conduct comprehensive audits of their ASA configurations to ensure that certificate-based authentication is properly implemented and that no unnecessary administrative access is exposed to external networks.