Several hundred pornography sites are surprising unwitting users with a smorgasbord of exploits via Mpack, the already notorious hacker toolkit that launched massive attacks earlier this week from a network of more than 10,000 compromised domains.

Trend Micro has spotted nearly 200 porn domains -- most dealing in incestuous content -- that have either been hacked or are purposefully redirecting users to servers hosting Mpack, a professional, Russian-made collection of exploits that comes complete with a management console.

Even though there are far fewer porn sites in this newly discovered infection chain than in Monday's "Italian Job" attack -- called that because most of the 10,000+ hijacked sites were legitimate Italian domains -- they've managed to infect twice as many end-users' PCs, said Trend Micro in a posting to its malware blog.

"Right now, we are not sure whether the porn sites are compromised to host the IFRAMES, are created to do so, or are being paid to host the IFRAMES," acknowledged Trend Micro. The attack probably began June 17, the company said.

Other researchers have continued to dig into the Mpack-based attacks and have shared some of their findings. Symantec, for instance, asked how hackers were able to infect so many sites in such a short time, and how they could inject the necessary IFRAMES code -- the malicious code they added to the legitimate sites' HTML that redirected visitors to the Mpack server -- so quickly.

"The MPack gang appears to be using an IFRAME manager tool to automate the task on a large scale," said Amado Hidalgo, a Symantec security analyst. The tool, which Hidalgo said was basically an FTP updater using MySQL as a back-end database, regularly checks a large list of sites to inject the malicious IFRAME code.

Hidalgo also spelled out how hackers have been getting into legitimate sites, which puzzled investigators earlier this week. "It takes as input a list of Web site administrator accounts, possibly obtained in the black market," he said. Those administrator accounts are recorded in MySQL, and the manager can be left running so that it re-infects sites that have been purged of the IFRAMES code. "A simple clean-up of the page is not sufficient," advised Hidalgo. "The site administrator's credentials need to be changed."

Sophos, meanwhile, analyzed the nearly 4,000 compromised sites it had found delivering the malicious IFRAMES code, and found that the overwhelming majority -- 98 percent to be exact -- were running the Apache Web server. "The servers targeted in this attack have almost exclusively been running some flavor of Apache on Unix," said a Sophos in a blog entry Friday. That's not always the case, said Ron O'Brien, senior security analyst at Sophos. "Overall, hacked sites are about evenly split between Apache and [Microsoft] IIS servers, but in this subset it's almost entirely Apache." Another interesting factoid, said O'Brien: "Of all the sites we've tracked that serve malicious code, about 80 percent have been hacked."

Still other researchers rooted out details of Mpack, including its price and the nom-de-plume of its creator. Ken Dunham, director of VeriSign-iDefense's rapid response team, said Mpack sells for around US$1,000, and that the man [or woman] behind it goes by "$ash" in the Russian hacker underground. The latest version of Mpack, .90, includes exploits for eight different vulnerabilities, six of them flaws in Windows or Internet Explorer, including the dangerous ANI bug that affected Vista earlier this year.

"This is a powerful Web exploitation tool," Dunham said.