Jailbroke! Native Linux support for F-Secure’s Freedome VPN

OpenVPN Interceptor - To use Freedome with any OpenVPN client

F-Secure’s Freedome VPN is notoriously locked down—no native Linux support, tightly bundled client… I jailbroke it so I can use it with raw OpenVPN configs using some light magick.

OpenVPN Interceptor - To use Freedome with any OpenVPN client

Preparation

Prerequisites you must download and install:

1. Download Wireshark and install it
2. Compile Console.MemGrep
3. Extract your client cert client.crt and key client.key (check C:\ProgramData\F-Secure\FSVpnSDK\keys as administrator), make copies as backup, and keep working copies somewhere else.
4. Extract the x1.crt file from C:\ProgramData\F-Secure

Get the private key password

1. Run Freedome, log in with your account, connect to the VPN
2. Open a PowerShell Console, get the PID of openvpn.exe ¹
3. Then run NETSTAT.EXE -aon | findstr <PID HERE> to get the local port openvpn is connected to.²
4. Open WireShark and set the filter to the port openvpn.exe is using ³
5. Reconnect and disconnect from the VPN
6. Analyse the capture, see thet openvpn.exe is used with -stdin and management mode ⁴
7. you will see the private key. ⁵

F-Secure Fights back!

Fsecure VPN works internally using the management console. FSVpnSDK sends command to openvpn.exe to setup the VPN. In order to fight against some people using a stub replacing the openvpn.exe, they added a check for the openvpn.exe digital signature, so one cannot replace the openvpn.exe to dump the commands sent to it. Also, they added a second layer of encyption to the private key using a proprietary algorithm (C:\ProgramData\F-Secure\FSVpnSDK\keys\client.key).

Using the openvpn.exe stub

In the latest version, FSVpnSDK checks the openvpn.exe digital signature so this wont work anymore

1. Compile the project
2. Run scripts/install.ps1, it will replace the openvpn.exe after making a backup
3. Run Freedome, log in with your account, connect to the VPN
4. Get your dumped config

💡 Advanced - Get Private Key #1

Because your private key is NOT ONLY encrypted using DES, but DOUBLY ENCRYPTED on disk using a proprietary algorithm so you cannot using it as-is with openvpn.exe. We need to get the clear version of the encrypted-base64 key we can use. The latter will then be decrypted using the password we got in wireshark ⁵

Having not idea how to decrypt it, I was trying to generate errors to get meaningful logs.

1. Disconect VPN, and break and invalidate my key ⁷
2. Monitor log files, check for ERROR, Warning, etc… ⁸
3. Reconnect VPN, waitin… BOUM! Good hint! The code looks for a string "</key>" in the decrypted text
4. Set the good key back using the backup we did earlier ⁹

Now we know the CLEAR TEXT of the Private Key has </key> Lets look in memory for it.

💡 Advanced - Get Private Key #2

To do this, you need my memory search tool console.memgrep

1. Search for a string in a specific process ¹⁰
2. Search for a string in a specific process, print data around found instance ¹¹
3. Search for a string in a specific process, print data around found instance ¹²
4. Get the size of data between 2 points ¹³
5. Dump only printable text around matches and write to file ¹⁴
6. Fix key format ¹⁵

List VPN using scripts

use scripts/Get-FSecureSiteList.ps1

Example configuration

If you have your private key, password, the CA cert already and the gateway you wish then you can replace values here .. code-block:

Important: comment out ; pull-filter ignore redirect-gateway That means the server does tell the client to redirect the traffic, but the client is still explicitly configured to ignore this push.

<ca>
CERTIFICATE HERE
</ca>
<key>
PRIVATE KEY HERE
</key>
cert <cert path here>
verb 4
client
dev tun
suppress-timestamps
preresolve
route-delay 0 12
push-peer-info
setenv UV_CLP peerid:2
replay-window 512 15
tcp-queue-limit 128
nobind
float
resolv-retry 20
server-poll-timeout 10
persist-key
mute-replay-warnings
remote-cert-tls server
data-ciphers AES-256-GCM:AES-128-GCM:AES-256-CBC
; comp-lzo
allow-compression no
cipher AES-256-CBC
auth SHA256
; pull-filter ignore redirect-gateway
<connection>
fragment 1400
remote freedome-ca-montreal.freedome-vpn.net 2747 
proto udp
explicit-exit-notify 1
</connection>
<connection>
remote freedome-ca-montreal.freedome-vpn.net 443 
proto tcp-client
</connection>

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About Guillaume Plante

A developper with a passion for technology, music, astronomy and art. Coding range: hardware/drivers, security, ai,. c/c++, powershell

Email : guillaumeplante.qc@gmail.com

Website : https://arsscriptum.ddns.net