Linux privileges escalade

To further escalate our privileges we will enumerate the machine for any vulnerable SUIDs. The SUID (Set User ID) bit is a permission in Unix-like operating systems that allows a program to run with the permissions of the file’s owner rather than the user who executed it. This means we can elevate our privileges if a binary that’s owned by root is misconfigured.

Search for SUIDs:

$ find / -perm -4000 2>/dev/null

2>/dev/null redirection is a good practice to filter any errors in the ouput. Means “send all errors to the mysterious /dev/null”.

SUID

If the binary has the SUID bit set, it does not drop the elevated privileges and may be abused to access the file system, escalate or maintain privileged access as a SUID backdoor. If it is used to run sh -p, omit the -p argument on systems like Debian (<= Stretch) that allow the default sh shell to run with SUID privileges.

This example creates a local SUID copy of the binary and runs it to maintain elevated privileges. To interact with an existing SUID binary skip the first command and run the program using its original path.

sudo install -m =xs $(which find) .

./find . -exec /bin/sh -p \; -quit