Businesses have been warned once again to protect themselves from the Code Red computer worm, after a new and more malicious version began circulating on the internet.
The Home Office said that the new version exploited the same flaw in Microsoft's IIS software and will not infect machines that have already downloaded a patch from Microsoft to protect against Code Red.
The worm gave hackers remote control of infected computers by leaving a "Trojan horse" in the system. It spreads up to six times faster than Code Red.
The new variant was identified by Uniras, a government agency that defends Britain's computing infrastructure from electronic attack, and the anti-virus software company Network Associates.
Uniras said that the worm's writers were likely to use infected machines as hop-points for hacking other systems, thereby making themselves more difficult to trace.
Uniras's website said: "This new threat is more dangerous than previous versions of Code Red though it is still unlikely to affect the whole internet infrastructure in the short term.
"Localised segments of the internet could be affected and performance degraded, and this might have serious consequences for communities of users affected."
The variant discovered yesterday concentrates on spreading locally rather than infecting any site across the internet.
It is difficult to detect and more complicated to remove than Code Red. Both worms exploit a flaw in a type of software that it used almost exclusively by businesses and thus does not affect home PC users.
The main effect of Code Red was to slow down the internet by creating excess traffic as the worm searched for vulnerable computer systems to infect.
On the 20th of each month, Code Red also launches a denial-of-service attack on the White House website, attempting to crash the site by flooding the server with requests. Some websites were also defaced with the words, "hacked by Chinese".
Code Red was believed to have hit more than 150,000 websites worldwide and sparked an unprecedented FBI warning, but it failed to degrade overall internet performance when it reactivited on August 1. A solution to the problem can be downloaded from the Microsoft website.
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Explained
Code Red worm
Comment
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Useful links
Code Red worm profile - Trend Micro Virus Encyclopaedia
Step-by-step instructions for eliminating the Code Red worm vulnerability - Digital Island
Here comes the Code Red hysteria
Information on "Code Red" IIS worm
Microsoft security bulletin offering patch for Code Red
CodeRed Scanner - eEye Digital Security
How to recover your system following an attack by Code Red - Cert
Things to remember when virus hysteria strikes - Vmyths.com
Here comes the Code Red hysteria - Vmyths.com
