CVE-2018-9105 - Improper Authentication

Severity

90%

Complexity

80%

Confidentiality

165%

NordVPN 3.3.10 for macOS suffers from a root privilege escalation vulnerability. The vulnerability stems from its privileged helper tool's implemented XPC service. This XPC service is responsible for receiving and processing new OpenVPN connection requests from the main application. Unfortunately this XPC service is not protected, which allows arbitrary applications to connect and send it XPC messages. An attacker can send a crafted XPC message to the privileged helper tool requesting it make a new OpenVPN connection. Because he or she controls the contents of the XPC message, the attacker can specify the location of the openvpn executable, which could point to something malicious they control located on disk. Without validation of the openvpn executable, this will give the attacker code execution in the context of the privileged helper tool.

NordVPN 3.3.10 for macOS suffers from a root privilege escalation vulnerability. The vulnerability stems from its privileged helper tool's implemented XPC service. This XPC service is responsible for receiving and processing new OpenVPN connection requests from the main application. Unfortunately this XPC service is not protected, which allows arbitrary applications to connect and send it XPC messages. An attacker can send a crafted XPC message to the privileged helper tool requesting it make a new OpenVPN connection. Because he or she controls the contents of the XPC message, the attacker can specify the location of the openvpn executable, which could point to something malicious they control located on disk. Without validation of the openvpn executable, this will give the attacker code execution in the context of the privileged helper tool.

CVSS 3.0 Base Score 8.8. CVSS Attack Vector: network. CVSS Attack Complexity: low. CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).

CVSS 2.0 Base Score 9. CVSS Attack Vector: network. CVSS Attack Complexity: low. CVSS Vector: (AV:N/AC:L/Au:S/C:C/I:C/A:C).

Demo Examples

Improper Authentication

CWE-287

The following code intends to ensure that the user is already logged in. If not, the code performs authentication with the user-provided username and password. If successful, it sets the loggedin and user cookies to "remember" that the user has already logged in. Finally, the code performs administrator tasks if the logged-in user has the "Administrator" username, as recorded in the user cookie.


               
}
}
ExitError("Error: you need to log in first");
);
);
DoAdministratorTasks();

Unfortunately, this code can be bypassed. The attacker can set the cookies independently so that the code does not check the username and password. The attacker could do this with an HTTP request containing headers such as:


               
[body of request]

By setting the loggedin cookie to "true", the attacker bypasses the entire authentication check. By using the "Administrator" value in the user cookie, the attacker also gains privileges to administer the software.

Improper Authentication

CWE-287

Overview

First reported 6 years ago

2018-03-27 23:29:00

Last updated 4 years ago

2020-05-11 18:38:00

Affected Software

NordVPN 3.3.10 for macOS

3.3.10
macos

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