Neosploit, the notorious hacker exploit kit, has returned to the web and is responsible for a dramatic increase in attacks, a security researcher has claimed.

"Neosploit's back," said Ian Amit, director of security research at Aladdin Knowledge Systems.

Neosploit, which first appeared in 2007, was a follow-on to the earlier MPack, and a contemporary to another infamous exploit kit, WebAttacker. Those kits, Neosploit included, were used by cybercriminals to launch attack code aimed at new vulnerabilities in Windows, Internet Explorer or third-party software such as Apple's QuickTime. But Neosploit also boasted features new to the click-to-attack business, including sophisticated statistical analysis and management tools.

In July researchers at RSA's FraudAction Research Labs said that they had evidence that the creators of Neosploit were abandoning the business. For proof, RSA quoted a going-out-of-business message said to have originated with Neosploit's authors.

However, even RSA didn't expect the Neosploit group to disband. "This isn't necessarily the end of this group," said Sean Brady, an RSA product marketing manager, in July.

A month ago, researchers at Aladdin started to suspect that the Neosploit developers were back in business. Two days ago, they uncovered hard evidence: A server hosted in Argentina, run by a longtime Neosploit customer that contained Neosploit 3.1. The build was dated August 9, just weeks after Neosploit's makers supposedly threw in the towel.

According to Amit, other data on the server showed that it was catering to 20 users, seven of whom he characterised as "very high volume", who were logging thousands of successful exploits each day from their use of Neosploit.

Those 20 criminals, added Amit, had compromised between 200 and 300 websites, which in turn were being used to serve up exploits from Neosploit to any visitor running a system that had not been fully patched. He found evidence of more than a quarter of a million successful attacks against PCs carried out by those sites.

"Neosploit's sole purpose is to deliver malicious code to browsers," Amit said, noting that site hacking isn't part of the kit's jobs. Instead, criminals compromise sites through other vulnerabilities or by gaming the site's administrative password. Only then do they modify the hacked site with attack code from Neosploit.

The kit also acts as a back-end analyser and is flush with tools that tell the hackers what exploits are most effective and which browsers are most vulnerable, features that have been significantly enhanced in version 3.1, Amit said.

NEXT PAGE: Improvements to the attack kit

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Neosploit, the notorious hacker exploit kit, has returned to the web and is responsible for a dramatic increase in attacks, a security researcher has claimed.

Another improvement, he added, was in licensing. "The main change I've noticed is that it locks down licensing even further. The 'criminal DRM' is even harsher than it was before," Amit said, adding that Neosploit had become so successful that it had been copied and pirated by criminals who didn't want to pay for the software. The licensing modifications, which include tying the username and password of a paying account to a specific IP address, is the group's reaction to that theft.

Neosploit's return, Amit said, coincides with a recent, rapid rise in the number of attacks targeting vulnerabilities in Adobe PDF files. Although other researchers, including those at Secure Computing, have speculated that the increase is due to a new PDF-only attack kit dubbed PDF Xploit Pack. Amit said the data dug out of the Argentinean server says otherwise.

"Now that we know Neosploit's back, we can try to correlate that with attacks in the last three to four months," Amit said. "The rise in the number of PDF exploits can definitely be linked to Neosploit 3.1." According to the data on the server, the PDF exploit Neosploit serves up is, by far, the most effective and efficient of those currently included with the kit. Neosploit 3.1 also tries other exploits, including ones aimed at QuickTime and Windows Media Player.

"We see one of these other kits [like PDT Xploit Pack] pop up once or twice a month, but they don't really catch on," Amit claimed.

Aladdin is working with both local and international law enforcement agencies to try to track the criminals using Neosploit, and shutter their servers, Amit said.

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