Solution for "SSL decryption bypass for Anydesk"

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Solution for "SSL decryption bypass for Anydesk"

L1 Bithead

Hello,

 

I am being asked a lot about why is Anydesk getting a "decrypt-error" end reason when SSL Decryption is active.

Here is a simple explanation and how to overcome this.

 

What you usually going to do with this kind of errors is creating a Decryption bypass rule for Anydesk (in this example)

Since is it impossible to bypass based on application, you would probably use a Custom URL category with a wildcard (*.anydesk.com), and apply it in a bypass rule. Unfortunately, this doesn't work (I'm not sure why, I think Anydesk uses IP addresses and not URLs)

The other option I came across is using an FQND (relays.net.anydesk.com) published in one of the related articles, that also didn't work for me. It was not consistent.

 

Then I found that Anydesk is being bypassed by default in PANOS (Device -->  Certificate management --> SSL Decryption Exclusion).

 

Then why isn't it being bypassed?!

Well, it is because of the certificate Anydesk uses. It is using a Self-Signed certificate, and your device does not trust it (yet).

This is the reason for the decrypt-error.

 

Basically, what you would like to do now is:

Start a packet capture and export the CA certificate.

Then, import the certificate to your device, and mark it as a trusted CA.

Commit, and now Anydesk should work.

 

I am sharing here the CA certificate currently being used by Anydesk.

 

Copy the text below to a text file and rename it to ".crt"

 

-----BEGIN CERTIFICATE-----
MIIFYzCCA0ugAwIBAgIJAIf7DQy3sYvoMA0GCSqGSIb3DQEBBQUAMEgxFzAVBgNV
BAMMDkFueU5ldCBSb290IENBMSAwHgYDVQQKDBdwaGlsYW5kcm8gU29mdHdhcmUg
R21iSDELMAkGA1UEBhMCREUwHhcNMTQwNDExMDIzNzU1WhcNMjQwNDA4MDIzNzU1
WjBIMRcwFQYDVQQDDA5BbnlOZXQgUm9vdCBDQTEgMB4GA1UECgwXcGhpbGFuZHJv
IFNvZnR3YXJlIEdtYkgxCzAJBgNVBAYTAkRFMIICIjANBgkqhkiG9w0BAQEFAAOC
Ag8AMIICCgKCAgEAtBVBDdoa01og/vnfvwqM8aSt79RUlufigrcNAOrxN+LXjKEW
O6BoCDiqbdsmvqZpkzaojh5w3KyBHuLdFoM0tRVw9YrNne5dgHxaeKIHpK7m+NYx
+lx7u+Ba61Evl7/2+zMnkLPY5ODNaDtqh2ymDefYvWHfVmsq4Rwr9Z+/hd2MWwYe
cX+6SqZAsHcX6iw/W5QUhS6tEWGriPYBu7NHa+KBGPGOOebYewxjhoOscIR1Jy01
PXt7qM6ySHkIOC2CJn6TSzJ2ZoWn/crxCi/HYg9qQP4aa1gcU+RjwXWDmqt4BEmD
H+cjcJ+jv2jRMy9M3l6GmH1hfQE09Zzpy0FrrlArZ9XZ8gL8X6NSNLncZ+/6c8WU
QOq1iveY7Oibu4ZsbzY3ioCMn4T2ykp2InKNUn2FdU1V762v8+UWIwBb6Lbtfp8u
gEvu1V/cZemJ3NumQwS7zv2pTC8ZM6rmcSCG/kWLl+bIHU9wusfAw/Om8trCpBvd
iU7sHNp7JI+qQvkUMoNoY8gmvOwTsw0L4rYIxsYGfqMWbxXSGxZSPB8ikSUXFcxC
gto7qDnHKlDK2UygjJUzdQNwuN+gybKyixs4g3kywxLaM5ZC9JERqsYmMbzqQ4ow
VGXFQ55QO/qRkw6dOyNKPUPBxiKbaK8v/AGAUhgFIg69auQuydbsxY/zE7MCAwEA
AaNQME4wHQYDVR0OBBYEFBlleQaAxt6yqliZV7I2XO0BYo1HMB8GA1UdIwQYMBaA
FBlleQaAxt6yqliZV7I2XO0BYo1HMAwGA1UdEwQFMAMBAf8wDQYJKoZIhvcNAQEF
BQADggIBALOqRxekr9JgNBWtJdWOKF7BqrGNMFabR3by4CBUBj3xI8Lvu6Hyn+Or
DAa/VF4MGjVWbeGTS8WZX5CGflKDlKCgRzby/PLCTXDJyW40XKcPBP3rFl6KvoY7
oAxzf6P1Xz0rxUEMZwrjSCvKYvapmh7J5ES8F/nbXEWYCWnsyGPvhSlOce35maxJ
IIqQvFmO8fOlmZkS46d75Wg0q1NarfFEyrp/wqZzkhDqjLHGydXkXisPHkqT+W1M
BoWQZVHTicwuomu15PDqNzWpfcDLhxIycpMhUYEdowzKlviB9JKgr/cZJPPmzeoR
KcnxKR2yKxgatKPAWMRwOXiniNd0MsKAYoNY47Q+JbhWLGB3UiWqYTLRl413JDQk
xdvy3WHI7WNXDsJw5R9S3WxvOLLa7Z2nL4f6s3DlZE35wwLVRtofy/BYIPxElvDK
tps55s8n0CyZdNTK3keI7d/3nDusimLSdZDZAIHT+MJHjpq9h23O5Zp/KHakd8Y/
ub9N8cvfDyxz/rRg4yZeg/KuNlaU6aedoT3KXW49Xahv8qWP855ohSfs6WeFNBYN
RTQUjgcMeyVRVPM/oSrvmheeUd4WZPvd4ciUCYw5u3dz1Ga7SStc+itXi2at96hw
O4+eCXHeEi7tAhBM1Wcecv86PjRtkmA9RF70IWDubC46cxrDJmr0
-----END CERTIFICATE-----

 

 

Hope this is helpful.

 

Cheers!

3 REPLIES 3

L4 Transporter

And idea is If you want you can remove Anydesk from the "SSL Decryption Exclusion" and test decrypting it and presenting the users with the trusted certificate as a workaround (they will not see the self signed cert in this way) just check also if the SSL decryption profile allows self signed certficates.

 

 

https://knowledgebase.paloaltonetworks.com/KCSArticleDetail?id=kA10g000000PPJfCAO

Due to client Certificate authentication, you cannot decrypt Anydesk.

This is Why is it added by PANW to "SSL Decryption exclusion" list.

 

The need to import the certificate into the NGFW is to make PANOS trust the self-signed certificate used by Anydesk server.

 

 

In this cas you are right that Palo Alto can't decrypt it.

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