An issue was discovered in Amazon AWS VPN Client 2.0.0. A TOCTOU race condition exists during the validation of VPN configuration files. This allows parameters outside of the AWS VPN Client allow list to be injected into the configuration file prior to the AWS VPN Client service (running as SYSTEM) processing the file. Dangerous arguments can be injected by a low-level user such as log, which allows an arbitrary destination to be specified for writing log files. This leads to an arbitrary file write as SYSTEM with partial control over the files content. This can be abused to cause an elevation of privilege or denial of service.

An issue was discovered in Amazon AWS VPN Client 2.0.0. It is possible to include a UNC path in the OpenVPN configuration file when referencing file paths for parameters (such as auth-user-pass). When this file is imported and the client attempts to validate the file path, it performs an open operation on the path and leaks the user's Net-NTLMv2 hash to an external server. This could be exploited by having a user open a crafted malicious ovpn configuration file.