One of the most important tools for a Red Teamer is the SOCKS Proxy. This enables the creation of a tunnel between two machines such that any network traffic forwarded through it appears to have originated from the target environments end. Once a foothold has been gained on a machine, a SOCKS proxy can be deployed between the operators machines and the target in order to access subnets, machines and services that would not normally be directly accessible. This includes being able to RDP to another machine or even to browse the corporate Intranet.
Nettitude have their own Socks proxy called SharpSocks by Rob Maslen which is incorporated with PoshC2, see the blog post about it here.
SOCKS support is built into most modern browsers and cURL. However, to use tools like rdesktop or nmap, proxychains on Linux can be used to tunnel the traffic. On Windows, software such as ProxyCap (http://www.proxycap.com/) can be used.
To start sharpsocks, enter the
sharpsocks command into a PowerShell Implant, which will provide the user with a command to run on the C2 server that will start the SOCKS server:
PS 1> sharpsocks /opt/PoshC2/SharpSocks/SharpSocksServerCore -c=CteIopoCcIfFegXFXsdzyscpt -k=O4QsWRPiEXYbHJobUSs9GfPloh9O8U7VlyV0dxYnWZ8= --verbose -l=http://127.0.0.1:49031 Are you ready to start the SharpSocks in the implant? (Y/n)
Once the SharpSocks server is running, press Enter, and the Implant will connect to the SharpSocks server. The SharpSocks server output will indicate when the implant has successfully connected and the SOCKS proxy has started.