The newspaper and social network were hit after their domain name details were maliciously edited by hackers.
The Syrian Electronic Army (SEA), a group supporting Syrian president Bashar al-Assad, says it carried out the attack.
It is the most severe attack so far carried out by the group.
In recent months, the hackers have targeted major media companies including the Financial Times, Washington Post, CNN and BBC.
But in this latest attack, the SEA was able to cause more sustained damage with a technique which also saw news and comment site the Huffington Post hit.
The attacked domains were managed by hosting company Melbourne IT, which has said it is looking at “additional layers of security” for protecting domain details.