CVE-2017-3840 in Secure Access Control System
Summary
by MITRE
A vulnerability in the web interface of the Cisco Secure Access Control System (ACS) could allow an unauthenticated, remote attacker to redirect a user to a malicious web page, aka an Open Redirect Vulnerability. More Information: CSCvc04849. Known Affected Releases: 5.8(2.5).
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Analysis
by VulDB Data Team • 12/25/2024
The vulnerability identified as CVE-2017-3840 represents a critical open redirect flaw within the web interface of Cisco Secure Access Control System version 5.8(2.5). This security weakness resides in the authentication and authorization mechanisms of the ACS platform, which is designed to provide network access control and user authentication services for enterprise environments. The vulnerability specifically affects the web-based management interface that administrators and users interact with to configure and manage access control policies. The flaw stems from insufficient validation of redirect parameters in the web application's response handling, allowing attackers to manipulate URL redirection behavior without proper authentication.
This vulnerability operates through a classic open redirect attack vector where an attacker can craft malicious URLs that, when clicked by an authenticated user, will redirect them to arbitrary web pages controlled by the attacker. The technical implementation involves the web application failing to properly sanitize or validate redirect URLs passed through HTTP parameters, particularly in authentication or session management contexts. The flaw can be exploited through various attack vectors including phishing emails, malicious websites, or compromised network resources that direct users to crafted URLs. The vulnerability is classified under CWE-601 as an Open Redirect vulnerability, which represents a well-known weakness in web application security where user-controllable input is used to redirect users to external sites without proper validation.
The operational impact of CVE-2017-3840 is significant within enterprise network environments that rely on Cisco ACS for access control. An unauthenticated attacker can leverage this vulnerability to conduct social engineering attacks, potentially compromising user credentials or redirecting users to phishing sites that appear legitimate. The attack can be particularly damaging in corporate environments where users trust the Cisco ACS interface and may not recognize the malicious redirection. When combined with other attack techniques such as credential harvesting or session hijacking, this vulnerability can provide attackers with elevated privileges or unauthorized access to network resources. The vulnerability affects the integrity of the authentication process and can undermine the trust model that Cisco ACS is designed to establish within network security infrastructures.
Mitigation strategies for CVE-2017-3840 should prioritize immediate patching of affected Cisco Secure Access Control System installations to version 5.8(2.5) or later, as this represents the official fix provided by Cisco. Network administrators should implement additional security controls such as web application firewalls that can detect and block suspicious redirect patterns, and establish strict monitoring of authentication logs for unusual redirect activity. Organizations should also consider implementing user education programs to raise awareness about phishing attacks and suspicious URL redirections. From a defensive perspective, this vulnerability aligns with ATT&CK technique T1566 which covers social engineering tactics, particularly phishing and pretexting. The remediation approach should include network segmentation to limit exposure, regular security assessments of web applications, and maintaining updated vulnerability management processes. The vulnerability demonstrates the critical importance of input validation and proper security coding practices in web application development, particularly in authentication and session management components that handle user redirects and navigation flows.