CVE-2018-0373 in AnyConnect Secure Mobility Client
Summary
by MITRE
A vulnerability in vpnva-6.sys for 32-bit Windows and vpnva64-6.sys for 64-bit Windows of Cisco AnyConnect Secure Mobility Client for Windows Desktop could allow an authenticated, local attacker to cause a denial of service (DoS) condition on an affected system. The vulnerability is due to improper validation of user-supplied data. An attacker could exploit this vulnerability by sending a malicious request to the application. A successful exploit could allow the attacker to cause a DoS condition on the affected system. Cisco Bug IDs: CSCvj47654.
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Analysis
by VulDB Data Team • 03/28/2023
The vulnerability identified as CVE-2018-0373 affects the Cisco AnyConnect Secure Mobility Client for Windows Desktop, specifically targeting the kernel-mode drivers vpnva-6.sys for 32-bit systems and vpnva64-6.sys for 64-bit systems. This represents a critical security flaw that undermines the integrity of the client software's kernel-level components, which are essential for establishing and maintaining secure network connections. The vulnerability resides within the driver's handling of user-supplied data, creating an exploitable condition that can be leveraged by authenticated local attackers to disrupt system operations.
The technical flaw stems from improper validation of user-supplied data within the kernel-mode driver components, which violates fundamental security principles outlined in CWE-20 - Improper Input Validation. When the vulnerable drivers process incoming requests, they fail to adequately sanitize or validate the data structures being passed to them, allowing malicious input to traverse the normal execution flow. This weakness enables attackers to craft specially formatted requests that, when processed by the driver, trigger unexpected behavior within the kernel space. The improper validation creates a pathway for attackers to manipulate the driver's execution context and potentially cause system instability.
From an operational perspective, this vulnerability presents a significant threat to enterprise security infrastructure as it allows authenticated local attackers to induce denial of service conditions on systems running vulnerable versions of the Cisco AnyConnect client. The impact extends beyond simple service interruption, as the DoS condition can potentially affect the entire network connectivity of affected endpoints. Attackers who have already gained local access to a system can leverage this vulnerability to disrupt the security client's operation, potentially forcing users to disconnect from secure networks and undermining the organization's security posture. This vulnerability particularly impacts environments where the AnyConnect client is widely deployed, as a single compromised endpoint could serve as a vector for broader service disruption.
The exploitation of this vulnerability aligns with techniques described in the ATT&CK framework under T1489 - Service Stop, where adversaries seek to disrupt services to achieve their objectives. The vulnerability's local attack vector means that attackers must first gain local system access, typically through credential compromise or other initial access methods, before they can execute the exploit. Organizations should consider this vulnerability in their threat modeling exercises, particularly when evaluating the risk of insider threats or compromised user accounts. The fact that this vulnerability affects both 32-bit and 64-bit systems indicates a widespread impact across different Windows architectures, requiring comprehensive patch management strategies across all affected environments.
Mitigation strategies should focus on immediate patch deployment through Cisco's official security advisories, as the vendor has released fixes to address the improper input validation issue in the affected driver components. System administrators should prioritize updating all instances of the Cisco AnyConnect client to versions that contain the necessary security patches. Additionally, organizations should implement monitoring solutions to detect anomalous behavior in kernel-mode components and consider implementing least privilege principles to limit local user access where possible. Network segmentation and endpoint protection solutions can provide additional defense-in-depth measures to detect and prevent exploitation attempts, while regular security assessments should verify that the patches have been properly applied across all affected systems.