CVE-2008-2736 in Adaptive Security Appliance 5500
Summary
by MITRE
Unspecified vulnerability in Cisco Adaptive Security Appliance (ASA) 5500 devices 8.0(3)15, 8.0(3)16, 8.1(1)4, and 8.1(1)5, when configured as a clientless SSL VPN endpoint, allows remote attackers to obtain usernames and passwords via unknown vectors, aka Bug ID CSCsq45636.
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Analysis
by VulDB Data Team • 08/16/2019
The vulnerability identified as CVE-2008-2736 represents a critical security flaw in Cisco Adaptive Security Appliance (ASA) 5500 series devices operating with specific software versions. This vulnerability specifically affects configurations where the ASA is deployed as a clientless SSL VPN endpoint, creating a significant attack surface that could be exploited by remote threat actors. The issue manifests as an unspecified weakness that enables unauthorized access to authentication credentials, fundamentally compromising the security posture of affected networks. The vulnerability was catalogued under Bug ID CSCsq45636, indicating it was recognized and tracked by Cisco's internal vulnerability management system. These particular software versions 8.0(3)15, 8.0(3)16, 8.1(1)4, and 8.1(1)5 represent a specific release lineage where the flaw was introduced or became exploitable through configuration changes. The clientless SSL VPN functionality allows users to access network resources through web browsers without requiring dedicated client software, making this attack vector particularly dangerous as it could be leveraged by attackers with minimal technical requirements.
The technical nature of this vulnerability involves an information disclosure weakness that occurs during the SSL VPN authentication process when the device operates in clientless mode. While the exact technical mechanism remains unspecified, such vulnerabilities typically involve improper handling of authentication tokens, session management flaws, or credential exposure during the SSL negotiation process. The flaw allows attackers to potentially capture or infer valid usernames and passwords without direct exploitation of the underlying authentication system. This type of vulnerability falls under the broader category of credential exposure issues that can be classified as CWE-200 (Information Exposure) or potentially CWE-522 (Insufficiently Protected Credentials) within the Common Weakness Enumeration framework. The attack vector suggests that remote unauthenticated users could potentially intercept or manipulate the SSL VPN session establishment process to extract authentication information. The vulnerability's impact is amplified by the fact that it affects multiple versions of the ASA software, indicating a systemic issue rather than an isolated bug that could be easily patched.
The operational impact of CVE-2008-2736 is severe and multifaceted, as it directly compromises the integrity of the authentication system for SSL VPN access. Organizations relying on clientless SSL VPN capabilities for remote access would face immediate risk of credential compromise, potentially allowing attackers to gain unauthorized access to corporate networks, internal resources, and sensitive data. The vulnerability's remote exploitability means that attackers do not need physical access or local network presence to exploit the flaw, making it particularly dangerous for organizations with distributed workforces relying on remote access solutions. This weakness could enable attackers to escalate privileges within the network, perform lateral movement, or conduct more sophisticated attacks using stolen credentials. The potential for credential reuse across multiple systems further amplifies the damage, as compromised credentials could provide access to various network segments, applications, and databases. From an operational standpoint, this vulnerability would likely trigger immediate security incidents requiring forensic analysis, credential rotation, and network access review processes.
Mitigation strategies for CVE-2008-2736 should prioritize immediate patching of affected ASA devices with the appropriate software updates from Cisco. Organizations must implement a comprehensive remediation plan that includes verifying the current software versions across all affected devices and applying the relevant security patches. Network administrators should consider implementing additional security controls such as multi-factor authentication for SSL VPN access, enhanced monitoring of VPN authentication events, and regular audit of user access logs to detect potential exploitation attempts. The vulnerability's nature suggests that organizations should also review their clientless SSL VPN configurations to ensure proper session management and authentication handling. From an ATT&CK framework perspective, this vulnerability aligns with techniques such as T1078 (Valid Accounts) and T1566 (Phishing) as attackers could potentially leverage stolen credentials to establish persistent access. Organizations should also implement network segmentation to limit the potential impact of credential compromise and consider deploying intrusion detection systems specifically configured to monitor for SSL VPN authentication anomalies. Regular security assessments and vulnerability scanning should be conducted to identify any other potentially affected devices or configurations within the network infrastructure.