$ cp /bin/ls /tmp/ikegami/
$ chmod 777 /tmp/ikegami/
$ chmod 700 /tmp/ikegami/ls
$ perl -T -e'%ENV=(PATH=>"/tmp/ikegami/"); system("ls") and die("error: $?");'
Insecure directory in $ENV{PATH} while running with -T switch at -e line 1.