CVE-2018-20193 in Secure Access SA
Summary
by MITRE
Certain Secure Access SA Series SSL VPN products (originally developed by Juniper Networks but now sold and supported by Pulse Secure, LLC) allow privilege escalation, as demonstrated by Secure Access SSL VPN SA-4000 5.1R5 (build 9627) 4.2 Release (build 7631). This occurs because appropriate controls are not performed. Specifically, it is possible for a readonly user to change the administrator user password by making a local copy of the /dana-admin/user/update.cgi page, changing the "user" value, and saving the changes.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 04/23/2020
This vulnerability affects Secure Access SA Series SSL VPN products previously developed by Juniper Networks and now maintained by Pulse Secure LLC, specifically targeting the SA-4000 device running firmware versions 5.1R5 and 4.2 Release. The flaw represents a critical privilege escalation issue that undermines the fundamental security controls designed to maintain user access segregation. The vulnerability stems from inadequate input validation and access control mechanisms within the web-based administrative interface, creating a path for unauthorized privilege elevation that directly violates established security principles and access control models.
The technical implementation of this vulnerability exploits a lack of proper authorization checks within the /dana-admin/user/update.cgi web script. A readonly user can bypass normal access controls by creating a local copy of this administrative page, modifying the user parameter value to target the administrator account, and then executing the modified script to change the administrator password. This represents a classic case of insufficient authorization validation where the system fails to verify whether the authenticated user possesses the necessary privileges to perform administrative operations. The vulnerability specifically relates to CWE-285 which addresses improper authorization in software systems, and demonstrates how weak access control validation can enable privilege escalation attacks.
The operational impact of this vulnerability is severe as it allows any authenticated user with readonly access to completely compromise the administrative account of the SSL VPN appliance. This creates a persistent backdoor that enables attackers to maintain long-term access to the network infrastructure while potentially gaining access to sensitive network resources. The vulnerability affects the core authentication and authorization mechanisms of the system, undermining the trust model that SSL VPN solutions are designed to provide. Attackers could leverage this to establish persistent access, escalate privileges further within the network, and potentially exfiltrate sensitive data or disrupt network operations.
Organizations should immediately implement mitigations including disabling unnecessary administrative web interfaces, enforcing strict access controls on administrative pages, and implementing network segmentation to limit access to administrative functions. The vulnerability highlights the importance of principle of least privilege and proper input validation as outlined in NIST SP 800-53 security controls. Network administrators should also consider implementing intrusion detection systems to monitor for suspicious administrative activities and ensure that all administrative interfaces require proper authentication and authorization checks. Regular security assessments and vulnerability scanning should be conducted to identify similar authorization bypass vulnerabilities in other network components and ensure compliance with security frameworks such as those defined in the MITRE ATT&CK framework for enterprise security.