It can be used to generate core dumps of running processes. Such files often contains sensitive information such as open files content, cryptographic keys, passwords, etc. This command produces a binary file named core.$PID, that is then often filtered with strings to narrow down relevant information.
It reads data from files, it may be used to do privileged reads or disclose files outside a restricted file system.
gcore $PIDIf 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 gcore) .
./gcore $PIDIf the binary is allowed to run as superuser by sudo, it does not drop the elevated privileges and may be used to access the file system, escalate or maintain privileged access.
sudo gcore $PID