this post was submitted on 09 Apr 2024
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Privacy

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Interesting findings within a VPN app (slrpnk.net)
submitted 7 months ago* (last edited 7 months ago) by [email protected] to c/[email protected]
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edit: please see comments for more informed insights.

I am currently investigating and reverse engineering free VPNs for a master thesis, and just came across something I thought I'd share. VPN in this case is 1clickvpn.net, not .com!

I'm sharing this as a warning as to never use free vpns! They are most often the opposite of what they promise to be. (by free I do not mean the free versions of premium services). But either way; be careful about your VPN choice, as they have access to a lot of sensitive data. I'm sure most peeps here know of this already, but next time you hear someone using a free vpn, let them know...

This first image/code was sitting inside a file called NetworkModule, with some hella weird external links.

  1. addrDOTcx, seems to have been linked to malware? Comes up flagged as malicious a few times on VirusTotal.
  2. freevpnDOTzone, seems to be another free possible malicious VPN service, might investigate this one later.
  3. bigbrolookDOTcom, seems to longer be a registered domain. But wtf? Was this VPN service linked to p*rn??
    IMAGE HERE; Don't visit these links unless you know what you're doing.

Furthermore, there is this interesting find; Now I am no expert coder, frankly quite the amateur. But does the below code really mean what I think it does? ~~Seems like it could be creating a fake connection?~~. This is more-less normal behaviour it seems, considering it is a local address it is probably used for testing purposes or making the app not crash if a connection cant be established. Is used once here;

Stay safe 🌻

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[–] [email protected] 37 points 7 months ago (1 children)

Probably not. It looks like it's setting the fake address before reading the tunnel parameters, where the real address is stored. Probably a kludge in case the connection address is undefined so the program doesn't crash. So check whether the address is included there.

Also check the function that establishes the connection. 10.1.1.1 is not a public subnet, so unless there is a VPN device listening at the local address, the tunnel should fail to establish and throw an error, triggering the exception clause in that code. Again, you'll want to confirm that in the code.

[–] [email protected] 29 points 7 months ago* (last edited 7 months ago) (2 children)

That seems to be the case, probably a killswitch-type feature, ensuring the VPN is working. Additionally, addr[.]cx is a free GeoIP lookup service, and I assume bigbrolook (OP - Big Brother is a term for a surveillance state, the porn definition is only used for 5-10 years) is/was another one. You can confirm with waybackmachine.

Seems to be an amateur free VPN using free infrastructure. Most of the time the free VPNs that turn their users machines into a proxy or do other dirty things will be obfuscated and require at least a bit of reverse engineering, not just opening a debugger and peeking.

Not trying to cast shade here, but isn't a master's thesis after you know a subject incredibly well, and aren't you supposed to look at things no one has looked at before? In case you're not in tech and this is a master's for another subject, this has been done.

[–] [email protected] 7 points 7 months ago (1 children)

Thanks for helping out! Totally should have thought of waybackmachine earlier.

Yes, a lot of these free VPNs seems to be baked with trackers too, and often built on the same infrastructure too.

Can't talk for all masters across all Uni's here, but at least in my country there is no strict requirement that it has to be something no one has ever looked at before, but it does need to be lesser known. While there is a lot of general research on VPNs - mostly the premium ones. There isn't a lot of peer-reviewed research on the free ones, at least not enough - as I had this topic approved by my Uni. Also, the prior research clearly showed that this is a growing problem, at those studies were back from 2016 and 2021. I therefore saw reason to further investigate the state of the free VPN landscape now again in 2024.

[–] [email protected] 1 points 7 months ago* (last edited 7 months ago) (1 children)

Thank you for doing the work. More of it needs to be done. I don't know what your workflow is, but running Android-x86 and injecting into the virtualbox networking process to strip the SSL should still work, unless the app uses certificate pinning. I wish I remembered the name of the program, but it's specifically for injecting into a running exe and hooking all network calls to pull ALL network data from that specific app. It's not Fiddler or Wireshark or any of those. Fiddler and wireshark will work fine if you add your self-signed cert to the Android CA list, as long as certificate pinning isn't used in the app. You can point wireshark to the virtualbox network adapter so it doesn't listen on your other adapters. Also, most apps in the app store, play store, and F-Droid likely will not have much maliciousness. Play Store has the highest chance. But I think you'll have better luck using all the major search engines and searching for "free VPN android" without any adblockers, using an android phone (Google & co easily detect user-agent manipulation) running chroming. Making note of all the paid ads, and then getting the first 10 pages of URLs, and then comb those links (all the ad links & result links) and download any .apk that shows up. Keep an eye out for more ads on those pages as well. Use a fresh android-x86 for each analyzed VPN apk.

There may be a better, easier way, but this was how I quickly analyzed the network data of android malware as of a few years ago.

Edit: other keywords to find shady vpns are ads for things like "watch porn in Utah" and "express VPN", " nord VPN", etc. You'll want to do the search within android as Google and Bing will allow the malvertisers to target specific operating systems, along with locations and other variables.

Also for checking into the servers that show up, and any interesting domains, you can use shodan and similar tools, and there is a great site (name escapes me now, similar to domaintools and urlscan.io though) that shows what domains run on certain IP addresses and also the owners and creation dates, although cloudflare and private whois entries make those less useful today. But that will potentially allow you to unmask 'networks' of shady free VPN providers.

[–] [email protected] 1 points 7 months ago

Thanks for this, will definitely incorporate some of this into my workflow!

[–] [email protected] 12 points 7 months ago (3 children)

BigBroLookDOTcom could be a reference to Orwell's 1948, rather than porn.

[–] [email protected] 5 points 7 months ago

1984, not 1948, in case anyone goes looking for the reference

[–] [email protected] 3 points 7 months ago

That’s pretty fucking funny β€œbig brother” was associated with porn rather than privacy.

[–] [email protected] -1 points 7 months ago* (last edited 7 months ago)

Ah indeed, good find!

[–] [email protected] 11 points 7 months ago* (last edited 7 months ago) (2 children)

Keep in mind the client doesn't have to do anything malicious, since it's their encryption - they could easily examine your traffic while it's on their infrastructure.

Third party VPN like this requires a high degree of trust.

[–] [email protected] 1 points 7 months ago

I believe it is easier to pull a man in the middle attack from the client

[–] [email protected] 0 points 7 months ago

Yeah! This VPN for instance too has their own proprietary protocol too...

[–] [email protected] 7 points 7 months ago* (last edited 7 months ago)

The addAddress call may just be configuring the local side of the VPN. It's hard to know without looking at the rest of the code.
The general workflow when establishing a VPN connection is:

  • open a socket to the destination VPN service (ProtonVPN, or whatever suspect service).
  • configure parameters such as DNS, split tunneling, and which networks to route over the VPN (generally everything from your local system, except the VPN connection itself).
  • update the local routing so traffic starts flowing over the VPN.

addAddress may just be part of the configuration. A very cursory search suggests that OpenVPN may be being used as the underlying VPN implementation framework (not uncommon).

[–] [email protected] 7 points 7 months ago (1 children)

All this really demonstrates is the dangers of drawing conclusions when you don't really have the skills to properly assess the information presented to you.

[–] [email protected] 7 points 7 months ago* (last edited 7 months ago)

I have not drawn any conclusions, nor will this be a part of the thesis directly. I am simply looking at the code for extra insights and learning. I wanted to share what I found because I am curious and want to learn. I'm open to constructive feedback, and by all means correct me - im just here to learn.

[–] [email protected] 4 points 7 months ago (1 children)

Why are you protecting them? Drop the fucking names lol. I literally do not understand.

[–] [email protected] 3 points 7 months ago (1 children)

1clickvpn.net, have edited the post.

[–] [email protected] 1 points 7 months ago

\ (β€’β—‘β€’) / thanks yo

[–] [email protected] 2 points 7 months ago

What is sad is that users would not care even when explained why "Fast Free VPN" from Play Store should not be used. It allows them to go to the blocked sites? Then it doesn't matter what else happens. It is very much understandable that people wouldn't want to pay, especially with current restrictions. If I didn't find a way to pay for my VPS, I would have rather gone for a charity-ran VPN or extension.

[–] [email protected] 2 points 7 months ago (1 children)

This is not a good post unless you specify what VPN you’re talking about.

[–] [email protected] 2 points 7 months ago

1clickvpn.net

[–] [email protected] 1 points 7 months ago

The local IP listed is probably the IP for all clients. You can do some magic with routing on the server side.