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Panda Protection

Virus Encyclopedia

Welcome to the Virus Encyclopedia of Panda Security.

Encyclopedia GetVirusCard True 0

HTML.Nimda

 
Threat LevelModerate threatDamageHighDistributionNot widespread
Common name:HTML.Nimda
Technical name:HTML/Nimda
Threat level:Low
Type:Worm
Effects:  It infects files with an EXE extension. It shares and grants access to all disk drives, allowing the free space on the disk drive to be used up.

 
Affected platforms:

Windows XP/2000/NT/ME/98/95

First detected on:Feb. 17, 2003
Detection updated on:March 21, 2003
StatisticsNo
Family:NIMDA

Brief Description 

    

HTML.Nimda is a dangerous worm, which is highly contagious and difficult to recognize. It spreads extremely quickly using its own methods, through the following means:

  • Web pages. HTML.Nimda uses the Web Directory Traversal Exploit in IIS Web servers  to modify pages written in the language HTML. It modifies these pages by inserting a script in them. When users access modified pages, they will be infected.
  • E-mail messages with an attachment called README.EXE. HTML.Nimda exploits a vulnerability in Internet Explorer (versions 5.01 and 5.5), which allows it to carry out its infection when the message carrying the virus is viewed in the Preview Pane
  • Networks of Windows computers (versions 2000 Pro, NT, 98, 95), in which HTML.Nimda can share the disk drives and spread to them.

The danger of HTML.Nimda lies in its capacity to spread and infect, which allows it to access all local disk drives (Windows 2000 Pro and Windows NT) and all the disk drives (Windows 98 and Windows 95) shared in a computer network.

Its aim is to spread to as many computers as possible and infect all the files with an EXE extension  that it finds. It activates when the user opens the programs Word and WordPad.

Visible Symptoms 

    

It is difficult to know if you have received the message carrying HTML.Nimda, regardless of the means of transmission used.

The only clear indication that HTML.Nimda has reached your computer is a file called README.EXE, which is attached to the e-mail messages that are infected with this virus.