While the Storm Worm has been used for denial-of-service attacks in the past, the ability to automatically attack any site that scans one of the botnet's nodes for vulnerabilities appears to be a recent development.
"I think they (the bot masters) are trying to prevent people from monitoring their bots and from downloading the (Storm Worm) file, because that is what they are trying to protect," said Joe Stewart, senior security researcher with SecureWorks.
The attacks are thought to be automated, rather than manual, because the surge in packets occurs almost immediately after an infected computer is scanned, he said.
"It is able to be triggered after a known set of actions," Stewart said. "It's not like the guy (bot master) wakes up three hours later and decides to DDoS in response."
The deluge of data comes after a vulnerability scanner attempts to check a compromised PC that is currently being used as a distribution node in the Storm Worm bot net. Such nodes serve up the files used by the Storm Worm to infect a PC and initiate a peer-to-peer connection with other infected systems. While the REN-ISAC warning specifically mentioned attacks on universities, Stewart would not say if companies had also been attacked.
Even school administrator balked at talking about the problem. Mark Bruhn, executive director for REN-ISAC, declined to describe the attacks or say who had been targeted, but said the warning needs to be heeded before information-technology departments become overwhelmed by returning students.
"We did pressure the parties involved in this situation to allow us to share quickly, because starting very soon, there will be millions of students returning to campuses with computers that have been connected to who-knows-where, and might be infected with who-knows-what," he said in a response to SecurityFocus' request for comment.
The REN-ISAC recommended that universities quickly respond to infections to minimise the chance that compromised systems become distribution nodes, which would trigger an attack. The group also recommended that schools monitor network utilisation for suspicious increases and have open communication channels with their internet service providers.
SecureWorks' Stewart also cautioned researchers to be careful of whom they scan.
"As a general rule, you always risk an attack whenever you go and probe people," he said. "Whether it is manual or automated, you always run that risk, so it is best to be prudent when scanning other networks, especially potentially malicious ones."
This article originally appeared in Security Focus.
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