10/14/2021 69 People found this article helpful 460,701 Views
Ultrasurf allows end users to circumvent gateway security devices like web filters and secure web gateways in order to surf the Internet without restrictions.
This article describes how to block UltraSurf versons 11.03 and above using App Control Advanced signatures.
Please Note: SID 7 is a firmware-based App Control signature and requires SonicOS 5.8.1.8-57o and above
This release includes significant user interface changes and many new features that are different from the SonicOS 6.2 and earlier firmware. The below resolution is for customers using SonicOS 6.5 firmware.
This article describes how to block UltraSurf versons 11.03 and above using App Control Advanced signatures.
Summary of configuration required to effectively block UltraSurf
The following table lists the application group or the signature IDs used to block UltraSurf:
Category | Application Name | Signature Name | Signature ID |
PROXY-ACCCESS | Encrypted Key Exchange | Random Encryption(Skype,UltraSurf,Emule) | 5 |
PROXY-ACCCESS | Encrypted Key Exchange | UDP Random Encryption(UltraSurf) | 7 |
PROXY-ACCCESS | Non-SSL Traffic over SSL Port | Traffic Anomaly Detection | 6 |
PROXY-ACCCESS | UltraSurf | UltraSurf Application Group | |
PROXY-ACCCESS | HTTP Proxy | HTTP Proxy Application Group |
NOTE
Enabling the above signatures has the unintended consequence of blocking outbound encrypted UDP packets which includes Skype traffic, SonicWall GVC connections and/or encrypted Syslog traffic to a GMS server. This is due to SID # 7 which blocks encrypted UDP packets. In the case of GVC connections this shouldn't be considered a drawback. Instead, it's a way to control unauthorised outbound VPN connections. Administrators can exclude remote gateway IP addresses and/or GMS server IP address from SID # 7.
This article illustrates how to enable the above signatures and how to exclude IP addresses from SID # 7.
Procedure:
Enabling DPI-SSL Client Inspection
NOTE:
Enabling DPI-SSL Client Inspection would entail a restart of the appliance; thereafter, DPI-SSL would re-sign all SSL/TLS connections passing through it. This could cause disruption in the network. Read the following article before enabling DPI-SSL CI : How to Configure Client DPI-SSL (Video Tutorial and KB Article)
Enabling Signature ID 5,6 & 7.
Enabling Application Block - UltraSurf
Enabling Application Signature Group - HTTP Proxy
Enabling Application Control on LAN zone
Excluding gateway IP addresses of SonicWall GVC from SID # 7
Signature ID 7 blocks encrypted UDP packets. SonicWall GVC connection uses UDP 4500 & 500. To allow GVC connections, exclude the gateway IP addresses of the GVC connection from SID # 7.
How to Test:
From a host behind the SonicWall start UltraSurf. UltraSurf will try to contact its servers and eventually fail.
The below resolution is for customers using SonicOS 6.2 and earlier firmware. For firewalls that are generation 6 and newer we suggest to upgrade to the latest general release of SonicOS 6.5 firmware.
Summary of configuration required to effectively block UltraSurf
The following table lists the application group or the signature IDs used to block UltraSurf:
Category | Application Name | Signature Name | Signature ID |
PROXY-ACCCESS | Encrypted Key Exchange | Random Encryption(Skype,UltraSurf,Emule) | 5 |
PROXY-ACCCESS | Encrypted Key Exchange | UDP Random Encryption(UltraSurf) | 7 |
PROXY-ACCCESS | Non-SSL Traffic over SSL Port | Traffic Anomaly Detection | 6 |
PROXY-ACCCESS | UltraSurf | UltraSurf Application Group | |
PROXY-ACCCESS | HTTP Proxy | HTTP Proxy Application Group |
NOTE
Enabling the above signatures has the unintended consequence of blocking outbound encrypted UDP packets which includes Skype traffic, SonicWall GVC connections and/or encrypted Syslog traffic to a GMS server. This is due to SID # 7 which blocks encrypted UDP packets. In the case of GVC connections this shouldn't be considered a drawback. Instead, it's a way to control unauthorised outbound VPN connections. Administrators can exclude remote gateway IP addresses and/or GMS server IP address from SID # 7.
This article illustrates how to enable the above signatures and how to exclude IP addresses from SID # 7.
Procedure:
Enabling DPI-SSL Client Inspection
NOTE:
Enabling DPI-SSL Client Inspection would entail a restart of the appliance; thereafter, DPI-SSL would re-sign all SSL/TLS connections passing through it. This could cause disruption in the network. Read the following article before enabling DPI-SSL CI : How to Configure Client DPI-SSL (Video Tutorial and Article)
Enabling Signature ID 5,6 & 7.
Enabling Application Signature Group - UltraSurf
Enabling Application Signature Group - HTTP Proxy
Enabling Application Control on LAN zone
Excluding gateway IP addresses of SonicWall GVC from SID # 7
Signature ID 7 blocks encrypted UDP packets. SonicWall GVC connection uses UDP 4500 & 500. To allow GVC connections, exclude the gateway IP addresses of the GVC connection from SID # 7.
How to Test:
From a host behind the SonicWall start UltraSurf. UltraSurf will try to contact its servers and eventually fail.
The following App Control messages will be logged under Log | View when UltraSurf traffic is detected and blocked: