If you are wondering, like me, what was the “timing attack” fix update in the latest 2.3.4 for, you can read this post here. Basically, if a comparison is made between two strings, it’s done one character at a time, and it stops when the first differing character is encountered. Therefore a potential hacker could measure how much time it takes to check a cookie hash to see if it’s correct or not.

It all seems far fetched, given that surely there must be the overhead in terms of routing from attacker’s PC to your server and Internet Protocol actually works that way that the packets are sent using different nodes, but there are guys who think it’s practical. It’s claimed that most Java programs are exposed under this theoretical vulnerability, so it’s actually not a problem particular to Rails.

However, the bad news about this 2.3.4 patch is that it doesn’t work under Ruby 1.9.1.