Site notice On Saturday, The Register suspended service by third party ad serving supplier, Falk, following security issues detailed here.

Falk fixed the problem within six hours of notification. Here is its summary of what went wrong:

Saturday, 20th November 2004 Falk eSolutions clients using AdSolution Global experienced problems with banner delivery between 6.10pm and 12.30pm GMT. This started on Saturday morning with a hacker attack on one of our load balancers. This attack made use of a weak point on this specific type of load balancer. The function of a load balancer is to evenly distribute requests to the multiple servers behind it. The system concerned was only used to handle a specific request type to our ad server and has now been investigated.

The use of a weak point in one of our load balancers led to user requests not being passed to the ad servers. Instead the user requests were answered with a 302 redirect to a compromised website. This happened with approximately every 30th request. Users visiting websites that carry banner advertising delivered by our system were periodically delivered a file from the compromised site. This file tries to execute the IE-Exploit function on the users' computer.