The article discusses various techniques for bypassing restricted shells, a controlled environment provided in Linux that has more limitations than a standard shell.
It covers the restrictions imposed by rbash, including limitations on directory changes, environment variables, and redirection of output, and then provides methods for overcoming these limitations.
The first two methods utilize various text editors with the capability to execute shell commands to exploit vulnerabilities and gain unrestricted access.
Further techniques include using programming languages like Python, Perl, or Awk to launch a linear shell and escalating privileges, establishing a reverse shell connection from the target machine to a listener on your machine, and then interacting with the shell through that connection.
The article also suggests leveraging system binaries like more, man, or less to interact with the shell and finally uses the Expect package to automate interaction with a shell.
Additionally, it suggests using SSH as a potential method for bypassing restricted shells.
Overall, this content outlines numerous strategies for lifting restrictions on shells in Linux environments and highlights the importance of security practices to mitigate these potential vulnerabilities.