Updated again A mass mailing email worm that contains exploit components from the infamous Code Red worm has appeared on the Internet, and appears to be spreading fast.
Nimda, which spreads though an infected email attachment, appears at the user's In-box with a random subject line and no body text. It comes with attachments called readme.exe and an HTML file. Users are advised to open neither and delete suspicious emails.
The malicious code contains an exploit string similar to that in the Code Red worm which is causing software tools that detect Code Red to "light up like Christmas trees", we hear.
MessageLabs, a managed services firm which scans its customers email for viruses, has intercepted 164 copies of the virus so far, after it first appeared this afternoon, possibly originating from Korea.
AV software vendors are busily updating their software to detect the worm. ®
An increase in port 80 scanning relating to the Nimda worm - which attempts to hit IIS boxes with many different exploits - has been reported by CERT. Its scanning activities might result in some overall slowdown of the Internet.
Central Command has published a more detailed description of the worm which states that although the body of an email appears blank, it contains code that will execute if a user views a message in either Outlook or Outlook Express.
To spread, Nimda uses MAPI (Mailing API) functions in order to extract email addresses, according to Central Command.
Another method to spread is by using a Unicode Web Traversal exploit similar to Code Blue targets which, as previously reported, tries to reprogramme systems previously infected by the Code Red worm.
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