CVE-2018-0334 in AnyConnect Network Access Manager
Summary
by MITRE
A vulnerability in the certificate management subsystem of Cisco AnyConnect Network Access Manager and of Cisco AnyConnect Secure Mobility Client for iOS, Mac OS X, Android, Windows, and Linux could allow an unauthenticated, remote attacker to bypass the TLS certificate check when downloading certain configuration files. The vulnerability is due to improper use of Simple Certificate Enrollment Protocol and improper server certificate validation. An attacker could exploit this vulnerability by preparing malicious profile and localization files for Cisco AnyConnect to use. A successful exploit could allow the attacker to remotely change the configuration profile, a certificate, or the localization data used by AnyConnect Secure Mobility Client. Cisco Bug IDs: CSCvh23141.
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Analysis
by VulDB Data Team • 12/26/2024
The vulnerability identified as CVE-2018-0334 resides within the certificate management subsystem of Cisco's AnyConnect Network Access Manager and Secure Mobility Client across multiple platforms including iOS, macOS, Android, Windows, and Linux operating systems. This security flaw represents a critical weakness in the authentication and validation processes that protect network access configurations. The vulnerability stems from improper implementation of the Simple Certificate Enrollment Protocol (SCEP) and flawed server certificate validation mechanisms that fail to adequately verify the authenticity and integrity of digital certificates during the configuration download process.
The technical exploitation of this vulnerability occurs through the manipulation of profile and localization files that Cisco AnyConnect clients download and process. When the client encounters these maliciously crafted files, the improper certificate validation allows an attacker to bypass the standard Transport Layer Security (TLS) certificate checking procedures. This weakness creates an attack vector where unauthenticated remote adversaries can manipulate the certificate validation flow, effectively allowing them to inject malicious configuration data, certificates, or localization information into the AnyConnect client environment. The vulnerability specifically affects the client-side certificate validation logic, which should normally verify that certificates are issued by trusted Certificate Authorities and that they properly validate the server's identity before accepting configuration data.
The operational impact of this vulnerability extends beyond simple configuration file manipulation to potentially enable more sophisticated attacks within the targeted network environment. An attacker who successfully exploits this vulnerability could modify the AnyConnect client configuration to redirect traffic through malicious servers, install compromised certificates that would allow for man-in-the-middle attacks, or alter localization data to confuse users and mask malicious activities. This capability directly undermines the security posture of organizations relying on AnyConnect for secure remote access, as it creates a persistent backdoor for attackers to maintain access and potentially escalate privileges within the network infrastructure. The vulnerability affects organizations using AnyConnect as their primary secure access solution, making it particularly dangerous for enterprises with remote work capabilities and distributed network access requirements.
Mitigation strategies for this vulnerability should focus on immediate patching of affected Cisco AnyConnect versions and implementation of additional network monitoring controls to detect unauthorized configuration changes. Organizations should ensure that all AnyConnect clients are updated to versions that address the certificate validation flaws, while also implementing network segmentation and monitoring to detect anomalous certificate validation patterns. The vulnerability aligns with CWE-295 which specifically addresses "Improper Certificate Validation" and relates to ATT&CK technique T1071.004 for application layer protocol usage and T1566 for credential access through social engineering or manipulation of client-side applications. Network administrators should also consider implementing additional certificate pinning mechanisms and regular security assessments of their remote access infrastructure to prevent exploitation of similar certificate validation weaknesses in other components of their security stack.