USPS officials have since taken down the Rapid Information Bulletin System pages for intelligent mail services, such as tracking and logistics.
Michael Sutton, vice president of research at Zscaler, which discovered the infected site and alerted the USPS, says the attack contained multiple payloads. "It's quite robust: It doesn't just have one or two payloads. We tracked down seven or eight, and it's intelligently delivering them," Sutton says. "Blackhole has done a good job at encrypting the payloads, and that's why [many antivirus packages] are not detecting it."
Researchers at Symantec say Blackhole is the most popular toolkit among website attackers and is the most prevalent one they have seen in the wild.
The kit was developed by Russian hackers and sells for $1,000 to $1,500. "It has a nice, neat, point-and-click interface," Zscaler's Sutton says. "It's popping up on a more frequent basis."
Last week, Zscaler revealed that it had been used to infect a Texas musical festival website, Worldfest.
Sutton says he's not sure what the attackers who hit the USPS site were after exactly, but the goal is to infect as many machines as possible, and attackers can use the Blackhole kit for various purposes.
"To me, this is the way attackers are doing things. They figured out end users are the weak point in the security chain. They're not trying to break into your servers -- they're trying to infect your end user machines," he says.
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