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09-21-2015 08:10 AM - edited 09-21-2015 08:11 AM
Hi all,
Does anybody already try with success to block Psiphon (https://www.psiphon3.com) ?
It's quite easy when psiphon is configured in VPN mode but how can I do that when VPN is not used ?
Thanks in advance for sharing.
V.
10-08-2015 12:39 AM
Hi all,
After opening a case, the answer is: Decryption enabled (blocking unsupported cypher-suite) + denying 'psiphon' application in security policy should be enough.
Need to be tested.
V.
09-21-2015 10:19 AM
Hello,
If you use some kind of web filtering, this should be able to block it on your network. I just checked the PAN-DB-URL and that url is:
09-22-2015 09:04 AM
Hi,
URL filtering can't be used because after "installing" the psiphon client, you need to initiate connexion.
These connexions are based on SSL then no URL filtering ... 😞
V.
09-22-2015 09:15 AM
Hello,
I do not know how the client works so I cannot see the traffic for myself. However you should still be able to see the URL's eventhough the traffic is SSL. Perhaps a submission for application detection is in order?
Custom signatures:
https://live.paloaltonetworks.com/t5/Documentation-Articles/Custom-Application-Signatures/ta-p/58625
Submit an application:
http://researchcenter.paloaltonetworks.com/submit-an-application/
Hope this helps...
09-22-2015 11:11 AM
Just in case you do use URL filtering:
URL: www.psiphon3.com
Previous category: computer-and-internet-info
You suggested: proxy-avoidance-and-anonymizers
New category: proxy-avoidance-and-anonymizers
The new categorization is available starting with URL DB version: 2015.09.22.220
Regards,
09-23-2015 06:19 AM
HI,
Thx for your help.
But it seem it's not enaugh for blocking psiphon 😞
I ask for new app.
V.
10-08-2015 12:39 AM
Hi all,
After opening a case, the answer is: Decryption enabled (blocking unsupported cypher-suite) + denying 'psiphon' application in security policy should be enough.
Need to be tested.
V.
10-08-2015 07:45 AM
Hi, can you elaborate more of your settings?
Decrypting all or just specific sites/url categories?
12-08-2015 12:19 AM - edited 12-08-2015 12:36 AM
Hi everyone.
In my experience SSL decryption and blocking the application Psiphon was not enough, it was only the first step. Psihon was stll able to connect. I discovered that Psiphon creates a Proxy service on localhost and changes proxy settings in browser to redirect browser traffic over Psiphon application. Psiphon application then forwards the traffic to the internet by its own sneaky methods:) I did Wireshark analysis and discovered that after SSL connection was blocked by PAN, Psiphon created a gzip encoded streaming tunel over tcp port 80 and PAN recognised it as "web-browsing" which was allowed. I tried to create a custom application but without success.
We successfully blocked the Psiphon by implementing SSL Decryption, blocking Psiphon application in the security policy and also by preventing users from changing their proxy settings using domain group policy.
Creating custom application signature for port 80 traffic and blocking it in the security policy on PAN would be more elegant but my signature caused too many false positives and it was easier to create a group policy.
LPM
12-10-2015 01:09 AM
Hello,
from my testing, blocking just Psiphon while using decryption was not enough. If you leave the client to try and connect long enough, it will still connect.
The best results I've got was by blocking the following:
http-proxy
ike
ipsec (not ipsec-udp)
l2tp
psiphon
ssh
ssh-tunnel
unknown-tcp
with application-default
Regards,
Stavros
12-10-2015 02:54 AM
There's actually an article about how to block psiphon :
How to Block the Psiphon application
If you feel it is incorrect please leave a comment there for review.
Hope this helps.
-Kim.
01-20-2016 07:10 AM - edited 01-20-2016 07:11 AM
Was it ever stated which category you need to decrypt? I dont want to decrypt anything except for what it takes to stop Psiphon.
03-28-2017 10:53 AM
Hi
I could block the Psiphon, with a security policy denying in application "psiphon/unknown-tcp/ssh" and SSL decrypt and to avoid the AutoProxy I made this
Click Run, and type regedit to open the Registry Editor. Find and open HKEY_CURRENT_USER\Software\Psiphon3, and on the right side you will see SkipProxySettings. Set this value to 1 and Psiphon will not automatically configure the system proxy settings.
10-05-2021 05:31 AM - edited 10-05-2021 05:31 AM
Hi,
additionally the unknown-udp application needs to be updated.
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