Adicione estas duas linhas no /etc/souces.list

# Brazil Mirror

# /etc/apt/sources.list :
deb https://ftp.br.debian.org/debian/ wheezy main contrib non-free
deb-src https://ftp.br.debian.org/debian/ wheezy main contrib non-free

Caso prefira servidor dos Estados Unidos adicione estas:

#United States Mirror

# /etc/apt/sources.list :
deb https://ftp.us.debian.org/debian/ wheezy main contrib non-free
deb-src https://ftp.us.debian.org/debian/ wheezy main contrib non-free

Fonte: https://how-to.linuxcareer.com/debian-apt-get-wheezy-sourceslist