Bot spreads through anti-virus, Windows flaws
Universities and schools worst hit
University security experts warned administrators on Monday that a bot program has started to spread by exploiting five patched Microsoft vulnerabilities and a six-month-old flaw in Symantec's anti-virus software.
The bot program, identified as W32.Spybot.ACYR by Symantec, has compromised a small number of systems at various universities, including about 30 systems at the University of Arkansas and another 150 systems at the University of New South Wales in Australia.
The spread of the bot software became noticed because of an inordinate amount of traffic to the network port number used by Symantec's software - both the Internet Storm Centre and the Research and Education Networking Information Sharing and Analysis Centre (REN-ISAC) reported spikes in traffic to port 2967.
While network data from the ISC and the REN-ISAC suggests that more than a 1,000 systems may have been compromised, an accurate tally was not immediately available.
"Our priority thus far has been to facilitate sharing protection and response information amongst our members," Douglas Pearson, technical director for the REN-ISAC, said in an email interview. "We've not yet developed an assessment of status and possible impact."
Bot software, which allows attackers to compromise and control a large number of computers, has become a major online threat and, increasingly, a favorite tool of cybercriminals. A recent surge in spam that started in August appears to be linked to the use of bots by online fraudsters.
The networks of compromised computers, or bot nets, created by bot software have typically exploited user naiveté and Windows flaws to spread further. Compromising a computer using a flaw in the security software designed to protect the system is a relative rarity. The best known case of such an attack is the Witty worm, which spread through vulnerable network security devices in April 2004.
The latest bot attack attempts to exploit five Windows vulnerabilities, although only one of the flaws - a security hole in the Windows Server Service - is recent. Of the other four vulnerabilities, one harks back to 2003, two to 2004, and the last from 2005, according to a Symantec analysis of the bot software.
Yet, the spread of the bot software came to notice because of its use of a flaw in Symantec's Client Security and Anti-virus Corporate Edition products. The flaw, fixed in May 2006, only affects some versions of the products. The company's Norton-branded security and system software are not affected by the flaw, so most home users are likely immune to the exploit.
Symantec, which owns SecurityFocus, warned its academic users early Tuesday morning through a notice on its web log. On Tuesday morning, the company released an updated anti-virus definition capable of reliably detecting the attack.
The company's network analysis system, DeepSight, detected a spike in traffic on port 2967 on Monday and at about noon ET on Tuesday. However, Symantec has only received four submitted reports of the malicious software so far - all from educational institutions, said Vincent Weafer, senior director of Symantec's Security Response Centre.
"From the enterprise point of view, no one is concerned - everyone has been patched for the last six months," Weafer said. "With the small number we are seeing..it could be that (the attackers) are just trying it out."
The Internet Storm Centre's assessment agreed that the bot software appears to only be spreading at a moderate pace and only among universities and colleges, with a few exceptions.
"The spam and the scanning seems to be widespread, while the reports of infection have come from edu's (educational institutions) and a few home users," Mike Poor, an incident handler at the Internet Storm Centre and a security analyst with Intelguardians, said in an email interview with SecurityFocus.
The slow infection speed surprised Scott Fendley, a security analyst with the University of Arkansas and an incident handler with the ISC. While Fendley estimated that thousands of the school's computers were vulnerable to the Symantec flaw, only about 30 systems were actually infected.
"We are currently attempting to understand why this did not propagate faster or infect other hosts on campus," he told SecurityFocus in an email interview.
The software does not appear to explicitly be targeting educational institutions, according to Symantec's Weafer (see correction). However, because schools have less strict policies regarding upgrading critical software, students and academic faculty may be the most vulnerable, Fendley said.
"As university environments are very decentralised, group policies and other mechanisms used to keep software up-to-date and well managed, may or may not exist," he said. "So one department may have completed the upgrades, when the office next door is still using a much older version."
Bots created with the the SpyBot software connect to Internet Relay Chat and await commands. The software attempts to detect if it's been quarantined in a honey pot by looking for the signs of a virtual machine and debugger software. The program uses the File Transfer Protocol to copy software onto compromised hosts.
Symantec recommended that users of its Client Security and Antivirus Corporate Edition update to the latest version of the software.
CORRECTION: The article attributed the assertion that the bot program was not explicitly targeting educational institutions to the wrong person. Vincent Weafer of Symantec stated that the attack did not seem to be targeted.
This article originally appeared in Security Focus.
Copyright © 2006, SecurityFocus