Welcome to the Virus Encyclopedia of Panda Security.
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. 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
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 worm is viewed through the Preview Pane
Networks of Windows computers (versions 2000 Pro, NT, 98, 95), in which Nimda can share the disk drives and spread to them.
The danger of 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.
It is difficult to know if you have received the message carrying Nimda, regardless of the means of transmission used.
The only clear indication that 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.