The Germany defence has been particularly leaky recently with four goals conceded against the USA and Sweden and five let in against Switzerland in the past 18 months.
"Joachim Low's team have conceded an average of 1.2 goals in their World Cup qualifiers to date," wrote Kahn in the Bild newspaper.
"That's far more than the other big football nations like the Netherlands, Spain or England."
Kahn believes Low's squad is too attack-minded and the thought of having to defend is alien to more than half of the 11 players out on the field.
"Spain have understood that, when possession is lost, all of the players must immediately defend with some good pressing and intelligent closing down of the gaps," continued the 44-year-old.
"Just to vary things, it doesn't harm if a long ball forward is played once in a while, like Mats Hummels regularly does for Dortmund."
Two of the three goals Germany conceded against Paraguay came from their attempts to play the ball out of their own penalty area whereas Kahn says the old route one would have been preferable.