The Flashback Trojan sometimes spreads through exploits like the Java vulnerability, but in the past it has spread as a fake Flash player update, which is how it got its name.
There's a bit of a personal history with this for me. For years, I've been at war with the Russian Zlob gang, the people who make the W32/Zlob malware and the Mac DNSchanger (aka RSplug, RSplugin.a, or OSX/Zlob) malware. I've been writing articles about how their malware distribution network works on my blog and in other places, and they've been reading my blog, using keywords and phrases from my blog on malware sites, and occasionally mailbombing me.
At the end of last year, police from many countries raided the Zlob gang and made a bunch of arrests in Estonia. All but one of the suspected members of the Zlob gang were arrested; the one who got away, a Russian, fled back to Russia.
The security articles I've been reading suggest that the Mac Flashback Trojan may have been written by the former Zlob gang member who evaded capture. There are coding similarities between Flashback and DNSchanger, the phony Flash installer that was used to install the DNSchanger malware is identical to the one used to install the first variants of Flashback, and interestingly, the same network of affiliates is being paid to spread Flashback. (In Eastern Europe, organized crime groups often pay people to spread malware. They set up affiliate networks of people who aren't directly part of the organized crime gang, who are given copies of the malware coded with an affiliate ID that they transmit when they infect a computer. The affiliates spread the malware however they can--by hacking legitimate Web sites and planting malware on them, by sending out spam, or by setting up fake sites with keywords that generate a lot of traffic--and are then paid a small fee every time an infected computer connects to a C&C server with their affiliate code.)
While it's difficult to be 100% sure, it *looks* like the guy who escaped capture in Estonia is setting himself up with a new crime gang and is responsible for Flashback.
