Parent class: VirWare

Viruses and worms are malicious programs that self-replicate on computers or via computer networks without the user being aware; each subsequent copy of such malicious programs is also able to self-replicate. Malicious programs which spread via networks or infect remote machines when commanded to do so by the “owner” (e.g. Backdoors) or programs that create multiple copies that are unable to self-replicate are not part of the Viruses and Worms subclass. The main characteristic used to determine whether or not a program is classified as a separate behaviour within the Viruses and Worms subclass is how the program propagates (i.e. how the malicious program spreads copies of itself via local or network resources.) Most known worms are spread as files sent as email attachments, via a link to a web or FTP resource, via a link sent in an ICQ or IRC message, via P2P file sharing networks etc. Some worms spread as network packets; these directly penetrate the computer memory, and the worm code is then activated. Worms use the following techniques to penetrate remote computers and launch copies of themselves: social engineering (for example, an email message suggesting the user opens an attached file), exploiting network configuration errors (such as copying to a fully accessible disk), and exploiting loopholes in operating system and application security. Viruses can be divided in accordance with the method used to infect a computer:
  • file viruses
  • boot sector viruses
  • macro viruses
  • script viruses
Any program within this subclass can have additional Trojan functions. It should also be noted that many worms use more than one method in order to spread copies via networks.

Class: Net-Worm

Net-Worms propagate via computer networks. The distinguishing feature of this type of worm is that it does not require user action in order to spread. This type of worm usually searches for critical vulnerabilities in software running on networked computers. In order to infect the computers on the network, the worm sends a specially crafted network packet (called an exploit) and as a result the worm code (or part of the worm code) penetrates the victim computer and activates. Sometimes the network packet only contains the part of the worm code which will download and run a file containing the main worm module. Some network worms use several exploits simultaneously to spread, thus increasing the speed at which they find victims.

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Platform: Linux

Linux is a family of UNIX-influenced operating systems based on the Linux kernel and GNU tools.


Technical Details

"Mighty" is an Internet worm that infects Linux machines running the popular "Apache" web server software. It does that by exploiting a vulnerability in the "Secure Sockets Layer" SSL "mod_ssl" interface code of the server which was originally reported on July 30, 2002, and listed by the Computer Emergency Response Team (CERT) as the Vulnerability Note VU#102795.

The configurations vulnerable to the specific exploit implementation used by the worm are Intel x86 Linux Apache installations with OpenSSL older than 0.9.6e and 0.9.7-beta. Updating to one of these two versions or other more recent releases will patch the vulnerability and prevent the worm from infecting the system.

The main worm replication component is about 19KB in size, and uses the exploit code from the popular "Slapper" worm.

Besides infecting more computers to spread further, the worm will also act as a backdoor on the victim system, connecting to an IRC server and joining a special channel from where it receives the orders. It's worth noticing the backdoor component of the worm is based on the popular 'Age of Kaiten' IRC bot source, used in many other IRC malware.

At the time of writing of this description, the worm is reported to have infected around 1600 systems worldwide.

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