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